Abstaract−In the present paper, we introduce and study the concepts of (i, j)−semi open set and (i, j)−semi neighborhood system in fuzzifying bitopological spaces. Also, the concepts of (i, j)−semi derived set and (i, j)−semi closure, (i, j)−semi interior, (i, j)−semi exterior, (i, j)−semi boundary operators in fuzzifying bitopological spaces are introduced and studied. Furthermore, we introduce and study the concepts of (i, j)−semi convergence of nets and (i, j)−semi convergence of filters in fuzzifying bitopological spaces