Citric acid is commercailly important product used in several industrial processes. Solid-state fermentation (SSF) has become an alternative method for citric acid production using agro-industrial residues such as cassava bagasse (CB). Use of CB as substrate can avoid the environmental problems caused by its disposal in the environment. The aim of this work was to verify the effect of different percentages of gelatinized starch in CB on production of citric acid by SSF in horizontal drum and tray-type bioreactors. Gelatinization was used in order to make the starch structure more susceptible to consumption by the fungus. The best results (26.9 g/100g of dry CB) were obtained in horizontal drum bioreactor using 100% gelatinized CB, although the tray-type bioreactor offers advantages and shows promise for large-scale citric acid production in terms of processing costs.