On account of its minimal expense and a high potential for change into energy-producing products, lignocellulosic biomass is the future of bioenergy and energy. Notwithstanding, their true capacity is restricted by the utilization of inefficient and unstable enzymes. Therefore, the present work aim to investigate the cellulose degradation potential of two isolated fungal species Aspergillus terreus and Trichoderma harzanium followed by bioethanol production from acid-thermal pre-treated rice straw (RS). The experiments were conducted in two phases. In phase-I of experiments, the isolated cellulose-degrading fungal species (Aspergillus terreus and Trichoderma harzanium) were employed for enzymatic hydrolysis of pretreated RS which was separated into two fractions namely: (Hydrolysate liquid) HL and (Residual pulp) RP. In phase-II of experiments, the enzymatically hydrolyzed substrate was subjected to yeast fermentation for bioethanol production. Using 18S rRNA sequencing, the microbial diversity study of the isolated species is covered in detail. The results revealed that the isolated fungal species A. terreus and T. harzanium resulted in 80 % of cellulose degradation. The highest bioethanol yield of 0.38 and 0.42 g/g of glucose was obtained from HL using Aspergillus terreus and Trichoderma harzanium treatment followed by yeast fermentation. The bioethanol yield of 0.17 g/g of cellulose was obtained from HL using both the fungal species.