Solid state sintering of cemented carbides is studied experimentally by means of dilatometry and SEM. Surface analysis of the powders is performed by means of ESCA, Auger and SIMS. It is concluded that for pure WC-Co mixtures the major part of densification occurs in the solid state and that high heating rates yield higher densification rates. 200 ppm of Ti, preferentially located at grain surfaces, yield a drastic decrease in sintering rate. Melting of the binder, i. e. transition to liquid phase sintering, only has a minor effect on densification rate.