Production of biodegradable plastic, polyhydroxyalkanoate (PHA) was demonstrated using culture of moderately haloakalitolerant Halomonas campisalis MCMB-1027. Production of PHA was carried out at different aeration (0.5-1, 1, and 1.5 vvm) and agitation (100,150 and 200 rpm) in 14 L fermenter. Maximum production of PHA was 40.69% on the basis of dry cell mass at 1 vvm and 100 rpm. Material balance over maltose revealed that aeration 1 vvm and agitation 100 rpm was optimum for conversion of utilized maltose into PHA. Controlled dissolved oxygen in the range 1-5% level during PHA accumulation phase facilitated to increase PHA content to 56.23%. A correlation equation was developed by fixing mass transfer coefficient (KLa) and applied successfully for scale up production of PHA in 120 L fermenter. 1H NMR analysis showed percentage of HB and HV unit 95.83 and 4.17 respectively.