The effect of mutagenic agents on Polyhydroxyalkanoates (PHA) accumulation was investigated in two micro-organisms Cupriavidus nectar and Kluyvera intermedia. Three mutagenic agents- ultraviolet light, heat, chemical mutagens (acriflavin and 5 bromouracil) were selected for the study. The cultures were treated at various time intervals and chemical at varying concentration and cultured using hydrolyzed grass (cyanodon dactylon) as a substrate. It was found that higher accumulation was obtained in C. nectar when treated at a concentration of 50µg/ ml acriflavin and 5 bromouracil (25µg/ ml). K. intermedia showed a higher accumulation at acriflavin concentration of just 25µg/ ml and 5- bromouracil at 50µg/ ml concentrations. It was observed that % PHA accumulation significantly decreased with increase in exposure to UV in both C. nectar (17 % - 1.18%) and K. intermedia (15 % - 7%). Exposure of culture to heat resulted in less PHA accumulation in C. nectar (16 % - 11%), K. intermedia (17 % - 19 %) compared to their parent strain C. nectar (17 %) and K. intermedia (25 %). FTIR spectra revealed the presence of characteristic medium chain length (mcl) PHA in the obtained sample.