A novel composite of the green microalga Chlorella sp. with polyethylene (PE) was synthesized through chemical modification of PE with maleic anhydride (MA), with respect to the biological fixation of CO2 with Chlorella sp. The interaction of Chlorella grains with a PE matrix is strikingly enhanced by the chemical modification of PE with MA. The tensile strength of a Chlorella-MA-modified PE composite (Ch-MPE) with a Chlorella content of 40 wt % is more than 2 times greater than that of a composite derived from unmodified PE. The marked increase in tensile strength is attributed to the formation of chemical bonds between Chlorella grains and the PE matrix, from IR and SEM studies. Because of the satisfactory thermal plasticity of Ch-MPE, it can be easily shaped into plate and dishlike moldings by a heat-pressurizing method. (C) 2004 Wiley Periodicals, Inc.