This review summarises developments in the photophysical properties of molecular metal complexes and their polynuclear and supramolecular assemblies for 2005. The huge increase in the popularity of this field (291 references included this year, compared to 145 last year) means that only the major high-impact journals have been covered. Particular highlights for the year (in the author’s opinion) include the following: single-molecule luminescence studies on very large multi-porphyrin oligomers containing up to 96 chromophores; achievement of exceptionally long near-IR luminescence lifetimes for lanthanide complexes using two quite different strategies; the demonstration of simultaneous multi-colour luminescence from metal complexes or complex assemblies using three different strategies; the detection of a picosecond-scale luminescence component from a simple [Ru(bpy)₃]²⁺ derivative arising from a non-thermalised excited state; and generation of long-lived charge-separated states of up to 1 second in a donor-chromophore-acceptor triad. Areas of particularly strong interest have been the generation and evaluation of new dyes for solar cells, and intensely phosphorescent complexes [usually of Ir(III) and Pt(II)] for use in OLEDs.