You are already connecting to the QProcess:finished() signal, so you will get notified when the process exits. As ChrisW67 says, no need to call QProcess::waitForFinished(). If there are things that Program A should not do while Program B is executing (like allow the "execBPushButton" to be clicked again), then you should disable it in the on_execBPushButton_clicked() slot and enable it again in the procFinished() slot.