The transport properties of over 400 Schottky diodes, fabricated on cleaved, atomically clean and on cleaved, air-exposed GaAs (110) surfaces, have been examined for a diverse range of metallisations using the conventional current-voltage and capacitance-voltage techniques. The resulting body of experimental data provides a reliable base for studying the correlation between the Schottky barrier height and fundamental quantities. In particular, the range of barrier heights obtained from the diodes fabricated on the clean surfaces are compared with the metal work function and the metal electronegativity. It is demonstrated that central transition metals, from groups Va-VIII of the periodic table, produce mid-gap Fermi-level pinning on GaAs. In contrast, the barrier heights extracted from simple- and noble-metal contacts, and from transition metals situated towards the beginning and end of a transition series, exhibit a near-linear dependence on electro-negativity. © 1988 IOP Publishing Ltd.