The main goal of this paper, divided into two sections, is to prove a theorem introduced in 1922 by the polish mathematician Kazimierz Kuratowski. This goal shall be accomplished in the second section of the paper with an argumentation, whose algebraic background has been prior exposed in the first section.

The Kuratowski Closure-Complement Theorem asserts that at most 14 sets can be constructed from a given subset A of a topological space and counting A itself by applying complementation and closure successively. It also exhibits on the real line a subset, for which this construction yields 14 different sets.

This paper is in fact a solution to the exercise submitted in a preceding article.