Carbon black (CB), a solid waste obtained from the pyrolysis of waste automobile tyres possesses a considerable heating value in it. In this study, four different emulsions of CB, diesel and water were prepared with the help of a surfactant, by varying the percentages of the CB. An emulsion containing 5% CB was denoted as CBWD5. Similarly, 10%, 15% and 20% CB in emulsion were denoted as CBWD10, CBWD15 and CBWD20, respectively. The emulsion were characterised for their suitability as fuels. Further, they were tested as alternative fuels in a single cylinder, air cooled, direct injection (DI), diesel engine developing power of 4.4 kW at 1500 rpm. The combustion, performance and emission characteristics of the diesel engine fueled with the four different emulsions were compared with the diesel operation of the same engine. The engine was able to run with all the four emulsions without any modification in the engine. The results indicated that the emulsions exhibited longer ignition delay about 1-3 degrees CA, compared to that of diesel at full load. The brake specific energy consumption (BSEC) was higher by about 0.8-25% with the emulsions than that of diesel at full load. The results also indicated that all the emulsions gave lower NO emissions by about 16-42% at full load. (C) 2014 Elsevier B.V. All rights reserved.