Bulk particulate solids subjected to compression and shearing may experience attrition and segregation of the debris which can cause amongst others dust hazards, difficulty in material handling and 'off-specification' products. This paper presents an experimental investigation on attrition of granular catalyst particles in an annular shear cell. By examining various models of attrition reported in the literature, we find that the model proposed by Neil and Bridgwater unifies our experimental data satisfactorily for the fine debris. The mass fraction of the fines produced can be described by a function of the normal stress, sigma, and the shear strain, Gamma, in the form of sigma Gamma (phi), where phi is a power law exponent. However, when the whole attrition products, including fine debris, coarse fragments and non-spherical particles, are considered, the trend of the experimental data does not satisfactorily follow Neil and Bridgwater's model. This implies that the process of particle fragmentation is not adequately described by this model. The experimental results also suggest that, if the normal stress is above a certain level, there exists a period at the initial stage of shearing, during which body fragmentation plays a significant role in particle breaking with the surface damage occurring to a lesser extent in the process. A theoretical analysis of the process has been carried out and will be reported later in another paper, where the two processes of surface damage and particle fragmentation are quantified and decoupled by the use of the distinct element analysis.