A polyaniline (PANi)/PANi-grafted multiwalled carbon nanotube (PANi/PANi-g-MWCNT) mixture was prepared by simple suspension (dynamic interfacial) polymerization. Scanning electron microscopy showed a two-phase mixture of PANi and PANi-g-MWCNTs while transmission electron microscopy of PANi-g-MWCNT showed a core–shell structure with outer PANi layer (5–10nm). Depending on the doping level, estimated by relative carbon content, the electrical conductivity of PANi/PANi-g-MWCNT was improved by more than four orders of magnitude over that of PANi. The composite also displayed high electrochemical activity with improved stability in an oxygen-saturated acidic solution.