Hexavalent chromium Cr(VI) compounds are highly toxic to the most life forms. Using cyanobacteria and microalgae as bioremediation agents can be a viable and cost-effective strategy to clean up chromium-contaminated sites without consumption of arable land and fresh water. Sixteen strains of cyanobacteria and microalgae were tested for tolerance against potassium dichromate (K2Cr2O7) and for their ability to bioremediate the most toxic form of Cr(VI). Dichromate bioadsorption capacity was tested under different growth conditions (medium composition, temperature, and light intensity) in order to obtain higher biomass yield and higher bioremediation yield for dichromate ion. Cyanothece sp. CCY110, a marine cyanobacterium, presented remarkable features in which it was able to tolerate up to 10 mg/L of dichromate. While exposure to 1 mg/L dichromate showed no significant effect on the biomass yield, exposure to 5 and 10 mg/L dichromate resulted in about 20 and 40% decrease in the biomass yield, respectively. The bioadsorption yield at 1, 5 and 10 mg/L dichromate was 26.4±0.5, 22.8±0.3 and 16.8±1 percent, respectively. The optimization process revealed that changes in media composition, temperature, and light intensity significantly changed the biomass production and bioadsorption yields, in which the highest bioadsorption and biomass production were achieved using ASNIII medium, 30°C, and 80 μEm-2s-1 light intensity. This resulted in more than 50% increase in the biomass production yield (OD600 of 0.624±0.007), and more than 100% increase in the bioadsorption yield (46.4±1.1%). This suggests that the marine Cyanothece sp. CCY110 has a great potential for large-scale bioremediation of K2Cr2O7 contaminated habitats.