Bioremediation of nickel by chlorophycean bioremediator, Chlorococcum hemicolum was investigated. The growth rates at various concentrations of Ni2+ were assessed in terms of protein level and 12 mg L-1 of the Ni2+ is the tolerance limit (46.76% level of growth kinetics). Absorption/adsorption kinetics was estimated after 240 h of Ni2+ treatments. Absorptions were higher than adsorption with maximum accumulation factor (AF) of 1.37. Ni2+ concentration and absorption were linearly related (r 0.98; p > 0.01). Other biochemical parameters like total sugar, chlorophyll and carotenoids were also quantified to correlate the state of metabolism and these exhibited reduction due to heavy metal stress. (C) 2007 Elsevier Ltd. All rights reserved.