This research is aimed at developing a temperature and moisture control system based on evaporative cooling and water replacement strategy in order to regulate the biomass productivity in the solid substrate fermentation of Rhizospus oligosporus on extruded corn. The process control scheme is based on adaptive control algorithm. The control system will be coupled to the estimation of biomass concentration and substrate conversion from on-line measured values of heat generation, oxygen consumption, carbon dioxide production, and water balance. Measured and estimated values will be correlated through mathematical modelling. Solid substrate fermentation (SSF) with filamentous fungi is a viable alternative to submerged fermentation if the process could be scaled up to industrial size and if the critical fermentation parameters can be measured on-line for process control purposes. The main problem in solid substrate fermentation is to regulated the temperature and the humidity in the fermenter so that the growth condition is optimized. It is proposed to do this by combining evaporative cooling and water addition as directed by a sophisticated "smart" controller. Process conditions are also to be estimated by mathematical models.