Hollow concrete masonry buildings represent an important part of the existing building stock. This type of construction is very widespread throughout the world and, in particular, it is widely used in Latin America. Hollow concrete masonry is versatile thanks to a large variety of available block sizes, the ease of assemblage and the good acoustic and thermal insulation properties. As it is well known, fibre-reinforced composite materials are established solutions for improving the structural behaviour of brick and stone masonry buildings. However, in the literature, there are only a few experimental and numerical data dealing with the strengthening of hollow concrete masonry buildings and, more particularly, concerning adhesion between composite materials and concrete blocks. This work covers an experimental investigation performed, by shear tests, on different types of fibre-reinforced composite materials applied to concrete blocks: a cement matrix combined with a bidirectional glass mesh (FRCM); a lime matrix assembled with a balanced bidirectional basalt mesh (FRLM) and a polymeric matrix combined with unidirectional carbon fibres (FRP). The experimental campaign aimed at evaluating the bond performance between the different composite materials while applied on the concrete block substrate. The investigation confirmed the good behaviour of the polymeric matrix composite in terms of load-carrying capacity and the cementitious matrix composite in terms of ductility. The lime mortar composite showed lower bond performance, but this composite deserves particular and more in-depth investigations in virtue of its good compatibility with masonry walls and its possible use for strengthening historical buildings.