The present study focussed on the increase in the quantity of acclimated microorganisms and biodegradability of synthetic oily wastewater in anaerobic environment. Acclimatization was carried out for a period of around seven months under batch mode. During the period of acclimatization, synthetic dextrose feed and synthetic oil feed were added to the anaerobic reactor at certain interval for proper growth of microorganisms. At the commencement of the process, there was addition of 100 mL dextrose feed to the reactor followed by decrease in the quantity of dextrose feed and increase in the amount of oil feed in different consecutive runs. Variations in different parameters including pH, Mixed Liquor Suspended Solid (MLSS), oil and grease as well as COD were observed in different batches. Out of ten ratios of synthetic feed for acclimatization, 40:60 and 0:100 were found to give the highest percentage removal of oil and COD respectively. There was inhibition from oil noticed after the ratio of 10:90.