The use of acids in the hydrolysis of starch for industrial and domestic purpose have become relatively unstable, expensive, difficult to control and even harmful to users over the years. This study aimed at isolating and characterizing alpha -amylase producing yeasts and investigate the effects of different cultural and physico-chemical parameters on the production of alpha- amylase. A total of forty- three (43) yeast strains were isolated from different fermented foods such as ogi, wara, palm wine and kunu. The isolates (OG9 and WR4) had the highest activity and were identified as: Candida tropicalis strain IFM 63517 and Candida tropicalis strain CMC 1836 respectively. Fermentation parameters such as incubation period, pH, temperature, effect of surfactants, carbon and nitrogen source were optimized using submerged fermentation. The optimum pH, temperature and incubation period for enzyme production were: 5.0, 30 °C and 48 hours respectively. Of the carbon sources, soluble starch at 1% concentration was observed to be the best carbon source for enzyme production using the two yeasts. Yeast extract at 1% concentration was ideal nitrogen source for the yeasts. Surfactants Tween-80 was most effective for enhancement of alpha amylase production. Cacl2 supported the highest alpha amylase activity for both strains. This study revealed that favourable fermentation conditions and the selection of suitable growth parameters played key roles in the production of alpha amylase by Candida tropicalis. Soluble starch is a good substrate for alpha amylase production. Alpha- amylase producing yeast strains with increasing enzyme activities at high temperature are promising candidates for industrial application.