Here, we study the continuity of integral operators with operator-valued kernels. Particularly we get L(q) (S;X) -> L(p) (T;Y) estimates under some natural conditions on the kernel k : T x S -> B (X, Y), where X and Y are Banach spaces, and (T, Sigma(T), mu) and (S, Sigma(S), nu) are positive measure spaces: Then, we apply these results to extend the well- known Fourier Multiplier theorems on Besov spaces.