The distribution function of ions during ion cyclotron resonance heating (ICRH) is studied analytically using a simplified one‐dimensional Fokker–Planck equation incorporating ion–ion and ion–electron collisions and rf quasilinear diffusion. By including source and loss terms in the equation, steady‐state and time‐dependent solutions, which are regular near the origin and vanish at high energies, are found. It is shown that an initially Maxwellian distribution function is transformed by the ICRH into a non‐Maxwellian distribution with a tail of energetic ions. The tail is more pronounced when quasilinear diffusion dominates over collisions and losses.