In this work we discuss the Data Handling electronics of the JEM-EUSO experiment, devoted to the study of UHE Cosmic Rays from space. The detector is composed of about 6000 multianode photomultipliers for a total of ≃2×105 channels. A multi-layer parallel architecture has been devised to handle the data flow and select valid triggers, reducing it to a rate compatible with downlink constraints. Each processing level filters the event with increasingly complex algorithms using ASIC, FPGAs and DSPs in this order to reject spurious events and reduce the data rate. The main CPU monitors the general acquisition of the experiment, handles the slow control and the interfaces to the Space Station. In this work are discussed the hardware solutions adopted to cope with the various constraints posed by this space borne detector.