The influence of gamma irradiation on gallium arsenide based photovoltaic cells was investigated. This type of solar cell is used for advanced space application where radiation degradation occurs in particular. A synthetic radioactive isotope of cobalt Co-60 was used with an applied dose of up to 500 kGy. These irradiation cause damage and degradation of the solar cell. A wide range of comparative characterisation methods was performed before and after irradiation. The effect of radiation on material morphology was described using electron and atomic force microscopy. Structural changes were investigated by Secondary Ion Mass Spectrometry (SIMS) with Time-of-Flight mass analysis (TOF) and Raman spectroscopy analysis. Also, the changes in noise fluctuations and current-voltage characteristics of the cell in the dark and under illumination were measured. Based on experimental measurements, the degradation was observed in the structural, optical and material cell properties as well as in electrical parameters.