The conventional processes for biodiesel production are highly energy intensive and time consuming because of mass transfer limitations in view of insolubility of oil in alcohols, makes a particular phase. Due to the less mass transfer in conventional process, free fatty acid (FFA) conversion to fatty acid methyl ester (FAME) is also decreased. This study is focused on biodiesel production through esterification of waste cooking oil by microbubble assisted para-toluene sulfonic acid (pTSA) catalyst. Microbubbles contain higher surface to volume ratio, increased interfacial area and high surface energy which lessens the mass transfer limitations and subsequently can increase conversion and rate of reaction. The conversion of FFA to FAME is studied by varying the reaction parameters including premixing time, catalyst ratio, molar ratio and reaction time of the process. While discussing about the said parameters effects on FFA conversion to FAME, 93.76% conversion is obtained at 40 minutes premixing time, 83.90% conversion is obtained by using 2gram catalyst, 82.09% conversion is observed by using 25 ml Methanol and 89.25% conversion is found to be after 10 minute reaction time.