To improve the performance of the single slope solar still an absorber plate with block shaped fins and a PCM chamber with slender shaped fins are used. Experimental investigations have been carried out. Two solar stills have been used simultaneously: a conventional solar still (CSS) and a new design solar still (NDSS). The influence of the depth of water and the mass of PCM on the performance of the modified solar still with PCM has been investigated. The fins were equipped in the basin of the solar still to augment evaporation of the basin water. To enhance the heat transfer between the phase change material and the absorber plate, slender shaped fins were welded on the upper of PCM’s chamber. The condensation of solar still was increased by using a secondary condenser on the shaded side of single slope solar still. The added secondary condenser was shielded to keep the surface of the condenser cool. It was found that the productivity of the modified solar still in comparison with conventional solar still was enhanced during day and night.