Let (R, m) be a commutative Noetherian local ring, M be a finitely generated R-module and a, I and J be ideals of R. We investigate the structure of formal local cohomology modules of F i a,I,J (M ) anď F i a,I,J (M ) with respect to a pair of ideals, for all i ≥ 0. The main subject of the paper is to study the finiteness properties and Artinianness of F i a,I,J (M ) andF i a,m,J (M ). We study the maximum and minimum integer i ∈ N such that F i a,m,J (M ) andF i a,m,J (M ) are not Artinian. We obtain some results involving cossuport, coassociated and attached primes for formal local cohomology modules with respect to a pair of ideals. Also, we give an criterion involving the concepts of finiteness and vanishing of formal local cohomology modules andČech-formal local cohomology modules with respect to a pair of ideals. *