The structural behaviour of Cu0.5Fe0.5Cr 2S4 has been studied experimentally and theoretically at pressures up to 44 GPa. The experiments are supported by density functional calculations using the full-potential linear muffin-tin orbital method for investigating ground state properties and high-pressure behaviour. We report here the first experimental and theoretical determinations of the bulk modulus: B0 = 106 (2) GPa and B'0 = 4.0 (experimental), and B 0 = 96 GPa and B'0 = 3.9 (calculated). Moreover, a pressure-induced structural and electronic phase transformation occurs at 14.5 GPa accompanied by a volume collapse of about 6%. Tentatively, the high-pressure phase is assigned the defect NiAs structure of Cr3S4 type with space group/2/m (12). The mechanism of the phase transition is explained by a Jahn-Teller type distortion, associated with geometrical frustration and magnetic spin changes. © 2013 Elsevier B.V. All rights reserved.