We have used electrically detected magnetic resonance (EDMR) to study the spin dependent processes on the operation of diodes based on poly(2-metoxy-5-(2'-etil-hexiloxy)-1,4-phenylene vinylene) (MEH-PPV) and on tris-8-hydroxyquinoline-aluminum (Alq₃). In MEH-PPV based diodes, the EDMR signal is found to be composed of two lines, a Lorentzian with ΔH_pp=5 G and a Gaussian with ΔH_pp=24 G. The g-factor of both components is about 2.0022. The signal is quenching, typically 10^-5 in amplitude, and is assigned to the spin-dependent fusion of two like-charged polarons to spinless bipolarons. The signal dependence on temperature and on injected current is investigated. For bipolar Alq₃ diodes the EDMR signal can be decomposed in at least two Gaussians, depending on the bias and temperature of measurements. The two components are characterized by g-factors close to 2.004 and a peak-to-peak linewidth (ΔH_pp) of 12 and 24 G, respectively. The broad line is attributed to the resonance in Alq anions, while the 12 G is attributed to cationic states