The characteristic equation showing the dependence of the steady‐state current for point‐to‐plane electrical corona discharges on the point‐to‐plane potential and other relevant parameters is derived. The mathematical model is based on hyperboloid point to plane geometry and assumes a constant charge‐carrier mobility with a constant potential drop across the corona glow region. The equation is an exact relationship for this geometry in that no calculation approximations are used in its derivation.