This study investigates the diagonal compressive response of cement-clay interlocking hollow brick masonry walls under in-plane shear loading. The main objective was to measure the effect of grout infill and vertical steel reinforcement to the shear capacity, deformation behavior, energy dissipation and failure mechanism of these walls where seismic as well as wind resistant masonries are constructed. Four wall specimens (1000 x1000x125)mm were tested under diagonal compression in four wall systems. Grout was prepared in the ratio of 1:2 (cement: sand) with slump of 220 mm, vertical Fe 500 steel rebars were used where mentioned. The combination of grout and reinforcement (W4) has shown to give the best response, with 119 % greater peak shear stress, the greatest initial stiffness and excellent ductility than W1. Different observed failure modes that were found ranged between brittle diagonal shear cracking in W1 and a distributed cracking, with local crushing in W4, meaning a better load redistribution and damage tolerance. Experimental results demonstrate that cement-clay interlocking hollow bricks, when combined with grout infill and vertical reinforcement, significantly enhance the in-plane shear capacity of masonry walls. This system provides a robust, sustainable solution for improving
structural resilience in seismic and high-wind regions.