A photophysical characterization based on optical high-resolution spectra and emission decay properties at low temperatures and at high magnetic fields is carried out for [Pt(s-thpy)(acac)] (s-thpy = 5,2-bis(2-thienyl)pyridinate and acac = acetylacetonate). The electronic 0-0 transition between the lowest triplet state and the ground state lies at 16 150 cm (1) (619 nm). The zero-field splitting (ZFS) of T-1 is smaller than 1 cm (1). Thus, the emitting excited state is mainly of ligand-centered (LC)-L-3((3)pi pi*) character and experiences only weak spin-orbit couplings to higher lying singlet states. The compound does not fulfill important requirements for OLED applications, but strategies for improvements are pointed out. (C) 2009 Elsevier B. V. All rights reserved.