Disposal of domestic wastes, such as waste cooking oil (WCO), without pretreatment, contributes to the deterioration of the environment and creating severs problems. Synthetic plastic poses threat to the environment, because it is non-biodegradable are now accumulate in the environment at great millions of tons per year.Bioplastic are polymers such as Poly -3-hydroxybutyrate (PHB), which has gained importance since it can be easily degrade in nature. The present study was aimed to isolate a promising microbial producer of (PHB), and optimization experiment to evaluate the best environmental and physiological factors that lead to maximum (PHB) production.Seventy Pseudomonas species were isolated from different contaminated soil and water samples. The isolates thereafter were screened for (PHB) production using Sudan black and Nile blue as indicators stains to investigate the bacterial isolates for PHB production. It was found that 50 of them were capable of producing PHB.The isolate Pseudomonas aeruginosa Dw 7 exhibit higher production of PHB, therefore it's selected for further studies. The isolate DW7 is definitively identified as Pseudomonas aeruginosa Dw7 after complete 16S rRNA gene sequences method. Highest accumulation of PHB and DCW were at 30°C, recorded 0.65 g/L and 1.78 g/l respectively with deletion of surface tension to 28mN/m with yield of PHB ranged between (35.6 and 36.5 %). Different WCO were tested as the sole carbon sources. The highest cell growth was observed on the polymer samples produced from corn oil, followed by the polymer produced using sunflower oil. The isolate yielded a relatively good dry weight 1.78 g/l with 0.72 of PHB yielding 40%