diff --git a/src/main/scala/ij_plugins/imagej_launcher/IJConfigFile.scala b/src/main/scala/ij_plugins/imagej_launcher/IJConfigFile.scala
new file mode 100644
index 0000000..203d9ca
--- /dev/null
+++ b/src/main/scala/ij_plugins/imagej_launcher/IJConfigFile.scala
@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2000-2023 Jarek Sacha. All Rights Reserved.
+ * Author's e-mail: jpsacha at gmail.com
+ */
+
+package ij_plugins.imagej_launcher
+
+import os.Path
+
+object IJConfigFile:
+
+  private val FileName: String         = "ImageJ.cfg"
+  private val MagicHeader: String      = "# ImageJ startup properties"
+  private val MaxHeapMBKey: String     = "maxheap.mb"
+  private val JvmArgsKey: String       = "jvmargs"
+  private val LegacyModeKey: String    = "legacy.mode"
+  private val AssignmentSymbol: String = "="
+  private val CommentSymbol: String    = "#"
+
+  /**
+   * Read `ImageJ.cfg` from a specified directory.
+   * The configuration file must be in ImageJ2 format (with magic header "# ImageJ startup properties").
+   *
+   * @param dir directory where `ImageJ.cfg` is located
+   * @param logger logger
+   * @return option containing the configuration file (Right).
+   *         The option is empty if file is not present in input `dir`.
+   *         An error message is returned if file is present but cannot be read without errors (Left).
+   */
+  def readFromDir(dir: Path)(using logger: Logger): Either[String, Option[IJCConfig]] =
+    logger.debug(s"Reading ImageJ configuration from directory: $dir")
+    val path = dir / FileName
+    logger.debug(s"  Looking for $FileName in: '$path'")
+    readFromFile(path)
+
+  private[imagej_launcher] def readFromFile(ijConfigFile: Path)(using logger: Logger): Either[String, Option[IJCConfig]] =
+    if os.exists(ijConfigFile) then
+      val lines = os.read.lines(ijConfigFile)
+      val cfgE =
+        lines.headOption match
+          case Some(line) =>
+            if line.trim.startsWith(MagicHeader) then
+              logger.debug(s"  Parsing $FileName")
+              for
+                props      <- parseProps(lines)
+                maxHeapMB  <- parseLong(props, MaxHeapMBKey)
+                jvmArgs    <- parseString(props, JvmArgsKey)
+                legacyMode <- parseBoolean(props, LegacyModeKey)
+              yield Option(IJCConfig(maxHeapMB, jvmArgs, legacyMode))
+            else
+              Left(s"$FileName is invalid, does not contain header: '$MagicHeader'")
+          case None =>
+            Left(s"$FileName is empty.")
+
+      // Add context to the error message, if there is one
+      cfgE.left.map(e => s"Failed to read $FileName. $e")
+    else
+      logger.debug(s"  $FileName not found: $ijConfigFile")
+      Right(None)
+
+  private[imagej_launcher] def parseProps(lines: Seq[String]): Either[String, Map[String, String]] =
+    // Parse each line
+    val lineResults: Seq[Either[String, (String, String)]] =
+      lines
+        .zipWithIndex
+        .filter { case (line, _) => !line.startsWith(CommentSymbol) }
+        .map { case (line, lineNumber) =>
+          val index = line.indexOf(AssignmentSymbol)
+          if index > 0 then
+            val key = line.substring(0, index).trim
+            if !key.isBlank then
+              Right(key -> line.substring(index + 1).trim)
+            else
+              Left(s"Error in line $lineNumber: key cannot be empty: '$line'")
+          else if index == 0 then
+            Left(s"Error in line $lineNumber: line cannot start with an assignment symbol '$AssignmentSymbol': '$line'")
+          else
+            Left(s"Error in line $lineNumber: no assignment symbol '$AssignmentSymbol' present: '$line'")
+        }
+
+    // Separate lines with errors
+    val errors = lineResults.collect { case e: Left[?, ?] => e }
+    if errors.isEmpty then
+      // Convert key->value pairs to a map
+      val r =
+        lineResults
+          .collect { case e: Right[?, ?] => e }
+          .map(_.value)
+          .toMap
+      Right(r)
+    else
+      Left(errors.map(_.value).mkString("\n"))
+
+  private def parseLong(props: Map[String, String], key: String): Either[String, Long] =
+    parseString(props, key).flatMap: s =>
+      s.toLongOption match
+        case Some(v) => Right(v)
+        case None    => Left(s"Failed to parse '$s' as an integer.")
+
+  private def parseString(props: Map[String, String], key: String): Either[String, String] =
+    props.get(key) match
+      case Some(v) => Right(v)
+      case None    => Left(s"No key named '$key'.")
+
+  private def parseBoolean(props: Map[String, String], key: String): Either[String, Boolean] =
+    parseString(props, key).flatMap: s =>
+      s.toBooleanOption match
+        case Some(v) => Right(v)
+        case None    => Left(s"Failed to parse '$s' as a boolean.")
+
+  /** Configuration loaded from `ImageJ.cfg`. */
+  case class IJCConfig(maxHeapMB: Long, jvmArgs: String, legacyMode: Boolean)
+
+end IJConfigFile
diff --git a/src/main/scala/ij_plugins/imagej_launcher/Launcher.scala b/src/main/scala/ij_plugins/imagej_launcher/Launcher.scala
index 2cb704c..56dde7b 100644
--- a/src/main/scala/ij_plugins/imagej_launcher/Launcher.scala
+++ b/src/main/scala/ij_plugins/imagej_launcher/Launcher.scala
@@ -13,7 +13,7 @@ import os.Path
 import java.io.File
 import java.lang.ProcessBuilder.Redirect
 
-class Launcher(logger: Logger):
+class Launcher(using logger: Logger):
 
   def run(config: Config): Unit =
     prepareLaunch(config) match
@@ -30,6 +30,7 @@ class Launcher(logger: Logger):
     for
       ijDir       <- IJDir.locate(config, logger)
       _           <- Updater.update(ijDir, config.dryRun, logger)
+      ijConfig    <- IJConfigFile.readFromDir(ijDir)
       launcherJar <- findImageJLauncherJar(ijDir.toIO)
       javaExe     <- locateJavaExecutable(config, ijDir.toIO)
       systemType  <- determineSystemType()
@@ -178,6 +179,7 @@ class Launcher(logger: Logger):
       "plugins",
       "net.imagej.Main"
     )
+  end buildCommandLine
 
   private def launch(command: Seq[String]): Unit =
     logger.debug("launchImageJ ...")
diff --git a/src/main/scala/ij_plugins/imagej_launcher/Main.scala b/src/main/scala/ij_plugins/imagej_launcher/Main.scala
index 355f25c..1ab084a 100644
--- a/src/main/scala/ij_plugins/imagej_launcher/Main.scala
+++ b/src/main/scala/ij_plugins/imagej_launcher/Main.scala
@@ -69,7 +69,7 @@ object Main:
 
   private def setupLogger(logLevel: Logger.Level): Unit = logger = new Logger(logLevel)
 
-  private def runLauncher(config: Config): Unit = new Launcher(logger).run(config)
+  private def runLauncher(config: Config): Unit = new Launcher(using logger).run(config)
 
   case class Config(
     logLevel: Logger.Level = Logger.Level.Error,
diff --git a/src/test/scala/ij_plugins/imagej_launcher/IJConfigFileTest.scala b/src/test/scala/ij_plugins/imagej_launcher/IJConfigFileTest.scala
new file mode 100644
index 0000000..f0260fe
--- /dev/null
+++ b/src/test/scala/ij_plugins/imagej_launcher/IJConfigFileTest.scala
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2000-2023 Jarek Sacha. All Rights Reserved.
+ * Author's e-mail: jpsacha at gmail.com
+ */
+
+package ij_plugins.imagej_launcher
+
+import org.scalatest.flatspec.AnyFlatSpec
+
+class IJConfigFileTest extends AnyFlatSpec:
+
+  given logger:Logger = new Logger(Logger.Level.All)
+
+  "IJConfigFile" should "read valid config files" in:
+    val path = os.pwd / "test" / "data" / "config_valid" / "ImageJ.cfg"
+
+    IJConfigFile.readFromFile(path) match
+      case Right(cfg) =>
+        logger.debug(cfg.toString)
+        assert(cfg.nonEmpty)
+      case Left(err) =>
+        logger.debug(s"Unexpected error: $err")
+        fail()
+
+  it should "fail reading invalid config files" in:
+    val path = os.pwd / "test" / "data" / "config_invalid" / "ImageJ.cfg"
+
+    IJConfigFile.readFromFile(path) match
+      case Right(cfg) =>
+        logger.debug(cfg.toString)
+        fail(s"Expected to return errors when reading config, but read config as: $cfg")
+      case Left(err) =>
+        logger.debug(s"Expected error\n:$err")
diff --git a/test/data/config_invalid/ImageJ.cfg b/test/data/config_invalid/ImageJ.cfg
new file mode 100644
index 0000000..9fc162e
--- /dev/null
+++ b/test/data/config_invalid/ImageJ.cfg
@@ -0,0 +1,4 @@
+# ImageJ startup properties
+maxheap.mb = 1024m
+jvmargs = -XX:+HeapDumpOnOutOfMemoryError -Xincgc
+legacy.mode = false
\ No newline at end of file
diff --git a/test/data/config_valid/ImageJ.cfg b/test/data/config_valid/ImageJ.cfg
new file mode 100644
index 0000000..5a40166
--- /dev/null
+++ b/test/data/config_valid/ImageJ.cfg
@@ -0,0 +1,4 @@
+# ImageJ startup properties
+maxheap.mb = 1024
+jvmargs = -XX:+HeapDumpOnOutOfMemoryError -Xincgc
+legacy.mode = false
\ No newline at end of file