The discharge of dye-containing effluents into the aquatic environment represents a source of aesthetic pollution with associated negative effects. Photocatalytic degradation has been identified as a suitable means of treating these effluents. In this study, the potential of a locally sourced material, periwinkle shell ash (PSA), has been explored as an effective photocatalyst for the photocatalytic decolourisation of tartrazine in aqueous solution. The efficiency of the photocatalyst was evaluated by investigating the effects of operational variables such as irradiation time, initial dye concentration and catalyst loading on the extent of decolourisation. The results show that the optimum levels of the variables were 50 minutes, 30 mg/L and 5 g/L for irradiation time, initial dye concentration and catalyst loading respectively. The pseudo first order and the Langmuir-Hinshelwood kinetic models were able to sufficiently describe the kinetics of the process. The diffusion mechanism was described by the intra-particle diffusion model while the adsorption equilibrium was described by the Langmuir isotherm equation. The results obtained indicate that PSA can be used as an effective photocatalyst for the removal of tartrazine from aqueous solution.