Due to the scarcity of potable water in some places and inability of available natural sources to fill the growing need for supplies of safe drinking water in addition to the high cost of energy used in saline water desalination. Pollution of fresh water resources by industrial wastes has heightened the problem. Solar energy is one promising solution to meet these ever-increasing demand clean and eco-friendly techniques should be used like solar distillation. This study is done to find the effect of PCM on solar distillation in a double slope solar still. The principle of pure water production from saline water using different designs of a solar water distillation technique is the same. A phase change material is a substance with high heat of fusion which, on melting and solidification is capable of storing and releasing a large amount of energy. In a double slope solar still, solar distillation was performed and the distillate output collected was recorded without using PCM. Some modifications were made to the solar still. Solar distillation was again performed in the solar still with different PCM. The amount of the distillate collected changes with many factors. The selection of PCM is an important step in the project. There are various things to consider before choosing a PCM. The theoretical model of the solar still system is developed. Through the various experiments performed on the solar still, various analysis were shown.