Nanoindentation was used to determine material hardness and Young's modulus in a wide compositional range of GaAsxP1-x, Ga1-xInxP, Ga1-xInxAs and Al0.5Ga1-xInxAs compound semiconductors. Ternary and quaternary samples were grown on misoriented GaAs(001) and Si(001) substrates by metallorganic vapor phase epitaxy. Nanoindentation measurements were made using a Berkovich shaped indenter in a continuous stiffness mode. This method allows a continuous measurement of modulus and hardness over the complete indentation depth. Parabolic and linear trends were found for the Young's modulus of the investigated compound semiconductors. In case of hardness, parabolic trends associated with solid solution strengthening were found for all investigated material systems. (C) 2013 Elsevier B. V. All rights reserved.