A facile one-step technique of preparing black polystyrene (PS) was developed by in situ suspension polymerization in which polymerization of styrene was conducted in the presence of modified carbon black (CB). A series of uniform black PS particles had been synthesized with this method. Morphology and dispersion stability of the various CBs were investigated by both scanning electron microscopy and spectrophotometric analysis. The results of thermogravimetric analysis indicated that the thermal stability of PS was significantly enhanced by introducing modified CB. In addition, the PS synthesized in the absence or presence of modified CB possessed a narrow molecular distribution, as was characterized by gel permeation chromatography. Compared with the conventional mechanical blending technique of PS and CB, our present technique could not only avoid the drawback of poor miscibility between the CB and PS, but also simplify the synthesis technique. Scanning electron microscopy micrographs of the resulting black PS demonstrated that modified CB was well dispersed in the PS matrix. POLYM. ENG. SCI., 51:294-301, 2011. (C) 2010 Society of Plastics Engineers