Fermentation in solid state was applied to woodchip and orange peel substrate aiming at cellulase production by utilizing Aspergillus niger fungus as a transformation agent. The study was conducted with the substrates alone, with different substrate fractions, and with the presence or absence of inorganic salts and carboxymethyl cellulose. Viability of the process was quantified by the yield of cellulase production. According to the results, orange peel was the substrate with the highest potential for enzymatic production, whereas woodchip was a viable substrate for cellulase production only when accompanied by orange peel. Carboxymethyl cellulose proved to be a strong advocate of cellulase production thusly positively influencing overall yield and increasing production to 53.2%; while nutrient supplementation acted in the opposite way, reducing the yield of enzyme production.