X-ray fluorescence has turned out to be a very suitable and reliable tool for the characterization of thin film chalcopyrite solar cells. Besides the composition determination in atomic percent the total mass per unit square (mg/cm(2)) of the analyzed elements and the film thickness can be measured accurately. Furthermore, a real multi-layer analysis allows in addition to determine the CdS, ZnO and Mo thickness simultaneously with the absorber measurement. By the use of etching techniques, information about a vertical composition gradient can also be obtained. This work shows the possibilities and limitations of the X-ray fluorescence technique for the chalcopyrite solar cell characterization and emphasizes the advantages over the widespread electron probe microanalysis.