Keywords: hydrogen peroxide bleaching, fibre strength, network strength, viscosity, tear strength, tensile strength, Single Fibre Fragmentation, zero-span tensile strength, fibre surface charge The study has focused on the correlation between pulp strength and single fibre strength, for hydrogen peroxide bleached pulp and if this correlation changes with changing bleaching conditions or bleaching chemical. Five methods were used to evaluate the network and single fibre properties; tear and tensile strength, pulp viscosity, Single Fibre Fragmentation (SFF), dry and rewetted zero-span and fibre surface charge. In addition to this %ISO brightness and Kappa number were measured. Softwood kraft pulp from the Värö mill was used in the study. The bleaching sequence used was (OO) Q (OP) Q (PO) and the samples were taken after the (OP) stage with reference samples taken after the initial (OO) stage and after the (PO) stage. The samples were then subjected to the final bleaching treatment in the laboratory. The results show that using hydrogen peroxide under optimum bleaching conditions i.e. a well-performed chelation treatment, a bleaching temperature of around 100°C and a reaction time of 3 hours produced a pulp of 87 %ISO at 25 kg H2O2/ton. Given this it is possible to produce a hydrogen peroxide bleached pulp that is just as strong as a chlorine dioxide bleached pulp. It has not been possible to establish a correlation between single fibre strength and fibre network properties. Results show that viscosity appears to be a rather good predictor of fibre network strength measured with tear/tensile tests. There are indications that zero-span does not evaluate single fibre properties but the strength properties of the fibre network instead. It was not possible to see any significant differences in SFF or fibre surface charge between the pulp samples.