There is a growing interest in using biodegradable green plastics polyhydroxybutyrate (PHB) produced by bacteria, which is seen as the most suitable alternative to conventional synthetic plastics. Also, using cheap agro-industrial wastes have attracted research and commercial interest worldwide. The present study aimed to isolate potent PHB producing bacteria and using whey as a low cost PHB production medium. Out of 20 bacterial isolates, 10 isolates were found to be PHB positive based on Sudan Black staining method. One potent bacterial isolate with maximum PHB (870 mg/l) was selected upon screening using whey medium which identified as Enterobacter cloacae DSM 30054 based on 16S rRNA sequence analysis. The culture medium and growth parameters of E. cloacae DSM 30054 were optimized for maximum PHB production.  Maximum PHB production (2186 mg/l) was achieved at 48 h when whey medium was supplemented with 3% sucrose and 1% sodium nitrate at pH 7.0, incubation temperature of 35 ̊ C, and inoculum size (2%).