#include <QApplication>
 #include <QTimer>

 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
     QTimer::singleShot(5000, &app, SLOT(quit()));
     ...
     return app.exec();
 }

import sys
from PyQt4 import QtCore, QtGui

app = QtGui.QApplication(sys.argv)
label = QtGui.QLabel("GUI")
label.show()

timer = QtCore.QTimer.singleShot(5000, quit)

app.exec_()

import sys
from PyQt4 import QtCore,QtGui

app = QtGui.QApplication(sys.argv)
label = QtGui.QLabel("GUI")

print "wait 5 seconds"
QtCore.QTimer.singleShot(5000,app,QtCore.SLOT(quit()))
print "5 seconds passed"
	
label.show()
sys.exit(app.exec_())