Four corn genotypes (UM.NF-3, UM.NF-5, UM.NF-9 and UM.NF-12) developed from the cross of field and sweet corns at university of Malaya; Malaysia was studied for their biochemical composition, calculated ethanol yield (CEY) and enzymatic hydrolysis yield. Biochemical components of grains varied significantly (p<0.05) with genotypic variation. Starch showed negative correlation with sugar (r = -0.793, p = 0.000) and protein (r = -0.558, p = 0.025). The maximum calculated ethanol yield (CEY) was found to be 4380.95 L ha1 in UM.NF-5 which coincided with having the highest grain yield (9.58 t ha-1) and starch content (73.33%). Two-step enzymatic hydrolysis yielded different reducing and total sugar concentration in the hydrolyzates that significantly (p<0.05) varied with genotype, particle sizes and solid-water ratio. Maximum reducing sugar was found in UM.NF-5 (179.83 g/L), while UM.NF-3 yielded the highest total sugar content (189.94 g/L) as a result of having the highest amount of grain sugar. The study has shown that higher sugar containing corn genotypes has the potential to be used for bioethanol production as it produces higher fermentable sugar yields after hydrolysis.