الملخص

     In this paper, we define ii-open set in bitopological space as follows: Let ( ,  , ) be a bitopological space, a subset A of  is   said to be ( – ii- open set )  if there exist  U,V ≠ and    U,V    such that: A=int1(U)                          or            A=int2 (V) A                 or      A       We study some characterizations and properties of this class.  Also, we explain the relation between ii- open sets and open sets, i-open sets and α-open sets in bitopological space. Furthermore, we define ii- continuous mapping on bitopological spaces with some properties.