Four edible Rhizopus strains were cultivated on eight combinations of solid agro-industrial wastes (cassava bagasse, apple pomace), soyabean, amaranth grain and soyabean oil. Significant differences in growth were observed among strains on the different media studied. The medium containing cassava bagasse with soyabean (5:5 w/w) gave the highest CO2 production, while Rhizopus oryzae ATCC 34612 was the best producer of volatiles. The aromas of the cultures were light and rather pleasant. The amaranth medium with mineral salts solution produced the highest amount of volatile compounds (VC), demonstrating that the aroma of fermented solid substrates can be improved. The VC production was very rapid, attaining, in most of the cases, its maximum around the first day of culture. These maxima markedly varied according to the medium used.