Synthesis of new functionalized oligosiloxanes and study of their photocrosslinking reaction in presence and absence of photoinitiators, have been carried out. Oligosiloxane monomers, capable of undergoing both radical as well as cationic photo-initiation, were synthesised. Other oligosiloxanes containing terminal groups such as maleimides and macroazoinitiators have been synthesised to be used as photoinitiators. The photo-induced crosslinking of silicones containing active groups in the presence of radical photoinitiator (TEPO from BASF), cationic photoinitiators (Cyracure^® UVI 6974 from Union Carbide and UV 9310C^® from GE Silicones) or of azoester or azoamide siloxane macroinitiators has been investigated by photocalorimetry. The influence of the photoinitiator type, siloxane molecular weights, temperature and of the exposure time on the photo-crosslinking kinetics is presented. Oligosiloxanes functionalized by maleimide groups in presence of donor systems also present a new way for the formation of new copolymers.