The Adaptive Gain Integrating Pixel Detector (AGIPD) is a hybrid pixel detector with bump-bonded silicon sensor, which is being developed for the European X-ray Free Electron Laser (XFEL). The XFEL provides photons in an energy range between 0.2 and 24.8 keV [1]. XFELs unique time structure comprises bunch trains at a repetition rate of 10 Hz, where each train consists of 2700 bunches with a temporal separation of 220 ns. Each bunch itself consists of ∼10¹² photons impinging in less than 100 fs. The challenges posed by this time structure will be addressed using a charge integrating device with dynamic gain switching and the possibility to store the analog signals on at least 200 storage cells. Up to now, three different prototype chips have been built, in order to investigate the different blocks of the final AGIPD chip. This paper will report on the results of the characterization of the first two prototype chips, namely AGIPD0.1 and AGIPD0.2. While the investigations on AGIPD0.1 focus on the readout chain (dynamic gain switching, linearity, etc.), the tests of AGIPD0.2 concentrate on the measurements involving the bump-bonded silicon sensor, such as the possibility of resolving single photons and pixel-to-pixel variations as well as the performance of the analog storage pipeline.