Statistics reveal that horizontal crushing strength data scatter in rather large ranges for cylindrical iron-based high-temperature water-gas shift catalyst tablets. This scattering is due to brittle fracture nature of the strength failure, originating from the stress concentration around edges of existing micro-cracks, such as pores, defects, and discontinuations contained in tablets. However, variations in the tablet size and density are found to contribute to strength data scattering. Data of tablet strength, height and density of the catalysts are found to be scattered in different ranges and to follow Weibull distribution, respectively. Based on the statistical data from a number of commercial catalysts, strength failure probability is proposed as the critical parameter for quality control. Catalyst tablet texture is examined, and it is observed that the tablets with strength close to low end of strength distribution have higher porosity, lower density and larger pore size in comparison with those near high end. For catalyst tablets, low strength is related to increased risk of strength failure, and high strength would result in lower catalyst efficiency. Catalyst tablet strength distributed in a narrow window is beneficial for commercial application. A correlation between catalyst tablet density and strength is established using a model proposed by Knudsen. Results obtained by analysing these interrelated parameters indicate that optimisation of catalyst tablet mechanical strength can be achieved through monitoring and controlling material properties and processing parameters during preparation.