The uncertain variables have been developed as a tool for decision making in a class of uncertain systems described by traditional models or by relational knowledge representations. The purpose of this paper is to show how the uncertain variables may be applied to specific optimization problems formulated for uncertain static plants. A general approach and the optimization with the given certainty threshold are described in the first part. In the second part the application of the presented approach to an optimal distribution problem is considered. Two examples illustrate the presented concepts.