The luminescence of the red (linear-chain) form of Pt(bpy)Cl-2 (bpy = 2,2'-bipyridine) has been measured as a function of hydrostatic pressure up to 30 kbar. The luminescence band maximum is red-shifted (158 cm(-1)/kbar), and the intrachain Pt(II)-Pt(II) distance decreases from 3.45 to 3.25 Angstrom, between ambient pressure and 17.5 kbar. Strong discontinuities in the emission energy, bandwidth, and intensity at 17.5 kbar are interpreted in terms of a crystallographic phase transition from the red to a yellow form of Pt(bpy)Cl-2. (C) 2003 Elsevier B.V. All rights reserved.