Future light sources based on high gain free electron lasers, require the production, acceleration and transport up to the undulator entrance of high brightness (low emittance, high peak current) electron bunches. Wake fields effects in accelerating sections and in magnetic bunch compressors typically contribute to emittance degradation, hence the photo-injector design and its operation is the leading edge for high quality beam production. The state of the art photoinjector beam brightness can be in principle brought above the 10^15 A/m2 threshold with an X-band gun and a proper emittance compensation scheme. We discuss in this talk an optimized design of a split X-band photoinjector, a convenient matching scheme with the downstream linac, based on the SPARC project experience, and the further technological developments required to reach such an appealing goal. A review of the INFN R&D activities concerning X-band accelerating structures, the SALAF program in the framework of the SPARX FEL project, will be also reported.
