In the present study, tolerance of ten microalgal strains isolated from wastewaters of different textile mills in relation to two metals and dyes was studied based on cell growth estimated spectrophotometrically. Three cyanobacterial strains that were found to tolerate both Cr(VI) and Co(II) along with the dyes reactive red 198 (RR 198) and crystal violet (CV) were investigated further for the concen- tration of various photosynthetic pigments and exopolymer production in the presence of the dyes and metals. All three tolerant species—Nostoc linckia HA-46, Myxosarcina spectabilis HP-43 and Gloeocapsa calcarea HP-45—showed a significantly higher concentration (P 0.05). Production of hydrogen by these photoautotrophic microbes was moderate (19-28 nmol h �1 mg �1 dry wt). The best performing strain, N. linckia, when examined further for its hydrogen production potential in the presence of the two dyes and metals, showed significantly higher rates of hydrogen production in the presence of Cr, Co and RR 198. Its hydrog- enase activity also followed the same trend. Immobilization of the microbe into alginate beads almost doubled the hydrogen production by the organism in the control as well as in the presence of suitable concentrations of the two metals (10 mg L �1 ) and dyes (50 mg L �1 ).