In this study, cooling performance of a refrigeration system under the effects of nanoparticle (TiO2) addition to the compressor oil (poly alkaline glycol (PAG)) was experimentally investigated. Thermodynamics analysis of the vapor-compression refrigeration system with various nanoparticle volume fractions of TiO2 (between 0.5%, and 1%) added to the compressor oil was performed. R-134a was used as the refrigerant. Two-step method was used to prepare the nano-lubricant for different solid particle volume fractions. It was observed that COP of the refrigeration system enhances with the addition of nanoparticles and it is an increasing function of nanoparticle volume fraction.