In this study, the thermal performance of the finned plate solar air heater (FPSAH) was investigated experimentally with using paraffin wax as phase change material (PCM). The proposed collector was manufactured and tested under weather circumstances of Tanta town (30° 47/ N, 31°E), Egypt. The effect of changing the mass flow rate on the instantaneous and daily efficiencies was also investigated. The influence of changing the mass of the PCM on the performance of the heater was also studied. The experimental results showed that the instantaneous and daily efficiencies of the FPSAH with and without using the PCM increases when the mass flow rate increases on the expense of the outlet temperature as it decreases. It is also found that the operation of the FPSAH extended up to 4h after sunset with outlet temperature reach 8.6°C more than ambient when 39kg of paraffin wax is used as latent heat storage. Depends on the results displayed in this study it is explored that using the PCM by the FPSAH improves the daily efficiency by 10.8–13.6%.