A two‐term expression consisting of a constant plus the product of an exponential and complementary error function is given for the transient reflected field of a horizontally polarized (Efield normal to the plane of incidence) plane wave in free space with a step‐function time variation incident obliquely on a plane imperfectly conducting surface. Curves computed with this expression are shown to be in good agreement with corresponding curves obtained numerically for all values of the time. Asymptotic expressions valid in early and late time are also given.