Effects of carbon sources, i.e. carbon nanotubes (CNTs), graphite, carbon black (C-black), on synthesised TiCx size, shape and compressive properties of in situ 40–60 vol.-% TiCx/2009Al composites were investigated. When CNTs and C-black were used, the synthesised TiCx with particle sizes of 0.08–1 and 0.9–5 µm, respectively, was spherical or nearly spherical in shape, while graphite was used, the synthesised TiCx with particles sizes of 0.2–2 µm was octahedral or spherical in shape. The yield strength (σ0.2), ultimate compression strength (σUCS) and hardness of TiCx/2009Al composites all increased with increasing TiCx content, while the plastic strain (ε) decreased. The σ0.2, σUCS, ε and hardness of 60 vol.-% TiCx/2009Al composites fabricated by using CNTs were 722 MPa, 946 MPa, 3.2% and 260 ± 10 Hv, respectively. The strength increase of the composites resulted from finer-sized TiCx particles with spherical shape. [ABSTRACT FROM AUTHOR]