In recent years, in order to satisfy the energy demand of increasing worldwide population, photoelectrochemical systems based on semiconductor electrodes have concentrated a lot of attention in research. In particular, catalyzing photoelectrochemical CO2 reduction represents a very attractive approach to harvest solar energy and recycle CO2 into fuels. CO2 can be converted into a wide variety of products, including several short-chain hydrocarbon substances such as HCOOH, CO, CH3OH and CH4. However, some of the major factors controlling product selectivity in CO2 reduction reaction are the chemical nature of the electrocatalytic or photoelectrocatalytic material and the type of solvent supporting electrolyte (SSE) system employed. Thus, powerful screening techniques are necessary in order to study the effect of electrocatalyst composition and SSE system. SECM is a probe electroanalytical technique, which employs an ultramicroelectrode (UME) or a micropipette probe (tip) to induce chemical changes and/or collect electrochemical information while approaching or scanning the surface of interest. When the UME tip is replaced by an optical fiber connected to a Xe light source, this local technique (photo-SECM [1]) can be used to individually address different photocatalytic spots and evaluate their individual photoelectrochemical activity by collecting the photocurrent generated. Nowadays, ionic liquids (ILs) represents a novel type of SSE system attracting a lot of attention for electrocatalytic CO2 conversion [2], since avoid concomitant H2 evolution reaction and present an interesting set of physicochemical properties, which include suitable ionic conductivity, high thermal stability, negligible vapor pressure and non-flammability. Therefore, the application of photo-SECM for rapid screening of photocatalytic materials in ILs represents a very powerful approach. We present here some new photo-SECM results, which allow to compare the photoelectrocatalytic activity for CO2 reduction on different semiconductor materials under UV illumination in 3 different media: i) aqueous solution, ii) water-IL mixture and iii) pure IL. The main drawback using imidazolium based ILs is due to their high viscosity, which limits CO2 diffusion and the maximum photocurrent density attained. For this reason, waterIL mixtures are also explored in order to overcome that limitation. [1] A.J. Bard, M.V. Mirkin (Eds.), Scanning Electrochemical Microscopy, second ed., CRC Press, Boca Raton, 2012. [2] C.M. Sánchez-Sánchez, Electrocatalytic Reduction of CO2 in Imidazolium-Based Ionic Liquids in Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry; K. Wandelt (Ed.), Elsevier, https://doi.org/10.1016/B978−0−12−409547−2.13377-3