This work goal is to simulate a solid-state fermentation bioreactor using a distributed parameter model to determinate cells growth, bed bioreactor temperature, substrate consumption, ethanol production, and CO2 and O2 produced by cells metabolism. All these process variables are dependent not only on time but also on bioreactor bed height. The modeling allows to observe the bioreactor fault, such as highest temperature point, which may hinder the process, and to develop control strategies and layouts that may avoid these gradients. The model proposed is composed by 1 Partial Differential Equation that describes the temperature profile, 3 Ordinary Differential Equations that describe cells growth, substrate consumption, and product yield, besides of 3 Algebraic Equations. The proposed model was discretized to describe the whole reactor behavior through time. Simulations have shown that as farther from the entrance of the bioreactor, the larger the temperature gradients were. In the reactor top were observed the highest temperatures. Such high temperatures affect the cells activity, since they deviate from their optimum condition, decreasing the substrate consumption and the product yield in the process.