NIR and IR spectroscopy has been applied for detection of chemical species and the nature of hydrogen bonding in arsenate complexes. The structure and spectral properties of copper(II) arsenate minerals: chalcophyllite and chenevixite are compared with copper(II) sulphate minerals: devilline, chalcoalumite and caledonite. Split NIR bands in the electronic spectrum of two ranges 11,700–8500cm −1 and 8500–7200m −1 confirm distortion of octahedral symmetry for Cu(II) in the arsenate complexes. The observed bands with maxima at 9860 and 7750cm −1 are assigned to Cu(II) transitions 2 B 1g → 2 B 2g and 2 B 1g → 2 A 1g . Overlapping bands in the NIR region 4500–4000cm −1 is the effect of multi-anions OH − , (AsO 4 ) 3− and (SO 4 ) 2− . The observation of broad and diffuse bands in the range 3700–2900cm −1 confirms strong hydrogen bonding in chalcophyllite relative to chenevixite. The position of the water bending vibrations indicates the water is strongly hydrogen bonded in the mineral structure. The strong absorption feature centred at 1644cm −1 in chalcophyllite indicates water is strongly hydrogen bonded in the mineral structure. The H 2 O-bending vibrations shift to low wavenumbers in chenevixite and an additional band observed at 1390cm −1 is related to carbonate impurity. The characterisation of IR spectra by ν 3 antisymmetric stretching vibrations of (SO 4 ) 2− and (AsO 4 ) 3 ions near 1100 and 800cm −1 respectively is the result of isomorphic substitution for arsenate by sulphate in both the minerals of chalcophyllite and chenevixite.