Optical absorption and luminescence of synthetic initial and neutron irradiated Gd 2 SiO 5 –Ce (0.5 mol.%) crystals was studied. Optical absorption spectra (1–6 eV) were measured using UV-Visible Helios Alpha spectrophotometer at T=300K. Time-resolved luminescence spectra (1.5–6 eV), luminescence excitation spectra (4–20 eV) and decay kinetics were recorded at SUPERLUMI station (DESY, Hamburg). Reactor neutron’s irradiation (fluence of 4⋅10 18 cm −2 ) leads to the effective production of defects. There were not registered any new luminescence bands in the irradiated samples, but radiation defects take significant part in the processes of energy transfer to luminescence centers.