Detailed experimental and theoretical studies of the electroluminescence excitation mechanism of Yb3+ in InP are presented. The electroluminescence spectra and the kinetics of Yb implanted InP were investigated under pulsed and dc excitations at temperatures over the range 9 - 70 K. The electroluminescence spectrum of the 4f transitions 2F5/2 - 2F7/2,, at 9 K, consists of a peak at 1001 nm and broader peaks in the spectral range between 1003 nm and 1010 nm. The intensity and current versus voltage characteristics have been recorded. The emission intensity increased linearly with current and started to saturate at high currents. The plot of the natural logarithm of intensity versus V−1/2 shows a straight line characteristic over three orders of emission intensity, showing that the direct impact excitation mechanism is a dominant process. At low temperature, the rise and decay times of the 1001 nm emission line were 9.63 µs and 10.50 µs, respectively. The thermal quenching energy, EA, was found to be 100 meV for both the electroluminescence intensity and the decay time.