Feedstock costs accounts for the larger percentage of biodiesel production cost. The use of less expensive feedstock and optimization of the process variables that affect the yield presents the opportunity of significantly reduction of this cost. This paper investigates the effect of temperature and catalyst concentration on the transesterification of Mango (Magnifera indica) seed oil with methanol using potassium hydroxide as catalyst. The biodiesel produced was characterized to ascertain its suitability for use as fuel. Results obtained showed that increase in temperature result in corresponding increase in the biodiesel yield. A yield of 83% wt was obtained at an optimum temperature of 60 °C. A similar trend was observed on the effect of catalyst concentration, with the optimum being 80%wt at 1% w/v. Analysis of the biodiesel produced showed consistency with the threshold standard values quoted by ASTM and EN for biodiesel and fossil diesel. This signifies that the biodiesel produced from mango seed is of good quality and can be used to consolidate the fossil based diesel.