The productivity of cyanobacteria Spirulina platensis and iodine accumulation in biomass at it cultivation in the pre-sence of KI with/without Co(NO3)2 have been determined. The supplementation in the first day is more favorable for obtaining of iodine enriched biomass. Iodine content is higher in biomass cultivated inthe presence of ratio KI: Co(NO3)2 as 12·10-3: 3·10-3 (mMoli).