Phase-modulated electrochemiluminescence (ECL), induced by modulating the applied potential, is reported for thin films of the metallopolymer, [Ru(bpy)2PVP10]2+, where bpy is 2,2′-bipyridyl and PVP is Poly 4-vinyl pyridine. Using a frequency of 0.25 Hz and an amplitude of 60 mV, a detection limit of 5 μM was obtained for oxalate which is a factor two lower than that obtained using a static DC potential. Significantly, the modulation technique shows higher sensitivity with a slope equal to 15.6 intensity units mM- 1 which is an order of magnitude larger than the unmodulated signal. The phase-modulated approach significantly increases the ECL signal-to-noise ratio, allows ECL measurements to be recorded under ambient light conditions and decreases the measurement time. © 2010 Elsevier B.V.