Picosecond Raman spectroscopy has been used to study non-equilibrium electron distributions and energy loss rate in a metal–organic-chemical-vapour-deposition-grown In_xGa_1−xAs_1−yN_y (x = 0.03 and y = 0.01) epilayer grown on GaAs substrate. It is demonstrated that for the photoexcited electron–hole pair density of electron distributions can be described very well by Fermi–Dirac distributions with effective electron temperatures substantially higher than the lattice temperature. From the measurement of electron temperature as a function of the pulse width of the excitation laser, the energy loss rate in In_xGa_1−xAs_1−yN_y is estimated to be about 64 meV ps⁻¹. These experimental results are compared with those of GaAs and important implications are given.