The formation of B-vitamins (nicotinic acid and nicotinamide, thiamine, vitamin B6 and vitamin B12) during the soaking of soybeans by bacteria, isolated from tempe, was investigated. Among the isolates examined no vitamin B6 producer was found. After inoculation of the soaking soybeans with Citrobacter freundii, Klebsiella pneumoniae, Pseudomonas fluorescens and Streptococcus spp. the concentrations of vitamin B12 increased significantly. For the first time it was found that soakings inoculated with C. freundii showed an increased vitamin B12 content. Nicotinic acid and nicotinamide were produced by Lactobacillus spp. and C. freundii. C. freundii synthesized thiamine as well.