This is the directory for storing thirdparty files. Please get following thirdparty files and put here. - QSerialDevice 2.0 Download QSerialDevice 2.0 from http://gitorious.org/qserialdevice/qserialdevice/trees/2.0 and deploy under Thirdparty/qt directory. The top directory for this thirdparty file will be "Thirdparty/qt/qserialdevice-qserialdevice". MEMO: If you develop on windows and use QtSDK with default configuration, you may encounter a build error "qwineventnotifier_p.h: No such file or directory." when you compile this thirdparty file. The easiest workaround for the issue is to install the source code of the Qt framework to QtSDK. You can do this by "Package Manager" which you can launch through QtCreator menu Help -> Update. The source seems to be copied under /QtSource. Copy the directory "src" under QtSource into the build package which you are using, they will be under /Desktop/Qt/4.8.0/mingw (or may be msv2010 or msv2008).