The surface charge of cellulosic fibre was determined using two methods . The relative surface charge (PTC) of three bleached pulps was quantified using polyelectrol to titration and compared with the absolute surface charge (So) measured by potentiometric titration. It was established that the polyelectrolyte titration method was a less tedious, but valid method of determining the surface charge of fibre, providing the titration method is standardised and the effect of variables such as suspension, pH, fibre concentration, ionic content and polyelectrolyte molar mass are eliminated. The method was used to construct a charge/pH isotherm of a bleached hardwood fibre similar to those constructed using potentiometric titration. Furthermore, the effect of refining of bleached hardwood and softwood krafts on the PTC was investigated.