The properties of the dynamic hysteresis loop of ac‐domain BaTiO3single crystal are examined as a function of temperature. Experimental results indicate that the coercivity and hysteresis losses decrease sharply as the crystal passes through a phase transition to a lower order of symmetry. This occurs without a substantial loss in loop rectangularity. The properties of a theoretical model for the hysteresis loop are derived from the Devonshire thermodynamic equations and previously defined experimental parameters. In the tetragonal and orthorhombic crystal phases, good agreement is obtained between the behavior predicted for the theoretical model and the experimental observations made on ac‐domain.