Abstract: The design models of isothermal batch and continuous stirred tank reactors are presented for bioremediation of crude oil in water environment. The reactor design equations were formulated based on conservation principle of mass and the reactor functional parameters simulated using MATLAB. The reactors were designed to treat crude oil at 95 to 99% degree of conversion with 79.5m3 volume of crude oil in water required to be treated daily. The results obtained showed that residence time for the batch reactor increased with increase in crude oil removed, which took approximately 2 hours. In addition, the heat generated per unit volume decreases with increase in residence time, which ranged from 6594 kJ/h.m3 to 6455 kJ/h.m3 at residence time of 1.904 to 1.984 hours and 95 to 99% crude oil removal. Similarly, the CTSR results showed that the volume and space time increased with increase in crude oil removed. The volume of CSTR ranged from 6.722 to 9.209m3, while space time ranged from 2.029 to 2.780 hours at 95 to 99% removal efficiency respectively. Conversely, the space velocity and heat generated per unit reactor volume decreased with increase in fractional conversion. The space velocity ranged from 0.493 to 0.36 h-1, while heat generated per unit reactor volume ranged from 1223 to 930.4kJ/hr.m3 at 95 to 99% removal efficiency respectively. Hence, the time required to remove one volume of crude oil fed into the reactor was higher in CSTR compared to the batch reactor, and at 79.5m3 of crude oil removal per day, the batch reactor will require 5 batches to complete the treatment. However, the heat generated per unit reactor volume was higher in batch reactor compared to the CSTR.