Sugar generation is important for many industries, such as livestock feed and bioethanol production. Rice straw is an agricultural waste that serves as a good source of sugar. In this study, a xylanase-producing fungus was isolated form compost pile and identified as Aspergillus fumigatus based on the internal transcribing spacer sequence. Xylanase produced by this fungus was characterised. The optimal conditions for fungal xylanase activity were 55C and pH 5.0. Enzyme activity declined to 45.26% following incubation at 50C for 2 days. Rice straw was more suitable for xylanase production than other substrates. The filtrate of A. fumigatus grown on rice straw as a substrate was added to rice straw, and reducing sugar production was determined. The maximum reducing sugar production was achieved with incubation at 30C for 18 h. Xylanase produced by A. fumigatus can be used for rice straw pre-treatment to improve the nutrient content of livestock feed and increase bioethanol production.