Reduction of manganese dioxide is not uniform throughout alkaline cells with thick cathodes. Quantification of the degree of reduction of MnO2 as a function of location in the cathode by determining the degree of EMD reduction in discharged alkaline cathodes is described, using a new experimental technique which allows collection and analysis of regionally defined electrolytic manganese dioxide (EMD) samples from commercial primary alkaline batteries of different sizes. This method has been developed for 1.5V D-size and C-size alkaline batteries. The information gained can be used to better explain the behaviour of real cells with thick cathodes.