Abstract. This article presents optimal fractional control. This control is based on the property of the invariance of a fractional order di¤erential equation. The problem formulation of the used control is expressed by di¤usive representation. The fractional control problem is described in a minimization form, where the global optimum represents the di¤usive realization of the controller. To determine the optimal fractional di¤usive control, an adaptive partitioning algorithm is used. As an application, we have chosen the control of a DC motor with uncertain parameters.