Due to the superior optical and electronic properties, all-inorganic perovskite materials have been widely used in optoelectronic device and energy conversion systems such as solar cells. However, photoelectrochemical devices with all-inorganic perovskite as photo-active material used in aqueous solution have been received not many attentions. In this work, the use of CsPbBr3 in photoelectrochemical system in direct contact with water is studied for the first time, considering also the post-mortem properties. Sub-micronic crystals of CsPbBr3 were synthetized by a conventional low temperature synthesis and the obtained materials were used to produce a photo-electrode for photo-electrochemical cell (PEC). The material was characterized and then tested to assess its electrochemical and photocatalysis properties. The particles showed high photocatalytic activity (more than 50% of Rhodamine degradation after 80 min) and promising photocurrent values of 11.7 mu A cm(-2) and 2.25 mu A cm(-2) in reduction and oxidation conditions respectively. The synthesis conditions assured CsPbBr3 good stability in water up to 60 min. After this time, system passes from pure CsPbBr3 to a mixture of CsPbBr3 and Cs4PbBr6 still retaining part of its photoelectrochemical activity. The results showed that CsPbBr3 has good potentiality as photo-electrode material in water-based photo electrochemical cell for the conversion of CO2 into fuels or chemicals.