Cellulase serves vast applications in the industries of biofuel, pulp and paper, detergent and textile. With the presence of its three components i.e. endoglucanase, exoglucanase and beta-glucosidase, the enzyme can effectively depolymerize the cellulose chains in lignocellulosic substrate to produce smaller sugar units that consist of cellobiose and glucose. Fungi are the most suitable cellulase producers attributing to its ability to produce a complete cellulase system. Solid state fermentation (SSF) by fungi is a preferable production route for cellulase as it imposes lower cost and enables the production of cellulase with higher titre. This article gives an overview on the major aspects of cellulase production via SSF by applying white-rot fungi (WRF) and brown-rot fungi (BRF), which include the type of lignocellulosic substrates for cellulase production, inoculum preparation and process conditions applied in SSF. The parameters that affect SSF production of cellulase such as fermentation medium, duration, pH, temperature and moisture content are highlighted. In addition, potential methods that can improve cellulase production, namely genetic modification, co-culture of different fungal strains, and development of bioreactors are also discussed. (C) 2014 Elsevier Ltd. All rights reserved.