Installing RXTX on Mac OS Mountain Lion

How to install RXTX Java library for Mountain Lion.

While trying to develop a Serial Port reading Java program I ran into a number of errors, mainly:

  • UnsatisfiedLinkError
  • dlopen(/Library/Java/Extensions/librxtxSerial.jnilib, 1): no suitable image found.

It took me a long time before I found any resources on how to do this so I decided to write one up when I finally got it working.

I’m not the most technical, so this is not too technical! In a nutshell, you are adding two files to the Java library on your Mac – RXTXComm.jar and librxtxSerial.jnilib

Hopefully it will help:

  1. Go to and download the binary version 2.1.7.
  2. Unzip the folder and place the unzipped folder on your desktop.
  3. Open the folder and navigate to the Mac_OS_X folder.
  4. Delete the librxtxSerial.jnilib file (I found that this file is using Java 5, and with Mountain Lion I was using Java 6).
  5. Go to Robert Harder’s blog and download his version of the librxtxSerial.jnilib file. Direct link here. Just want to say thank you to Robert for his blog post – it saved me big time. What he has done is compiled a Java 6 friendly version of librxtxSerial.jnilib.
  6. Save this new librxtxSerial.jnilib file in the Mac_OS_X folder of the RXTX folder you have on your desktop from step 2.
  7. Open Terminal and type the following:

cd <where you unpacked it>/rxtx-2.1-7-bins-r2/

sudo cp RXTXcomm.jar /Library/Java/Extensions

sudo cp Mac_OS_X/librxtxSerial.jnilib /Library/Java/Extensions

Now you shouldn’t have any more RXTX errors when compiling your Java program.

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