The electrogenerated chemiluminescence (ECL) of platinum (II) octaethyl-porphyrin (PtOEP) in acetonitrile:methylene chloride (CH 3 CN:CH 2 Cl 2 , 50:50 v/v) and CH 2 Cl 2 is reported. ECL was generated upon sweep to positive potentials using tri-n-propylamine (TPrA) as an oxidative–reductive coreactant. ECL efficiencies (ϕ ecl ) of 0.18 in CH 3 CN:CH 2 Cl 2 (50:50 v/v) and 3.90 in methylene chloride were obtained using Ru(bpy) 3 (PF 6 ) 2 (bpy=2,2′-bipyridine) as a relative standard (ϕ ecl =1). The ECL intensity peaks at a potential corresponding to oxidation of PtOEP and TPrA, and ECL emission spectra are nearly identical to photoluminescence emission spectra, indicating that emission is from the PtOEP triplet state.