Abstract
The main objective of this paper is to study the classical Hermite-Hadamard-type inequalities for Riemann-liouville fractional integrals. The Hermite-Hadamard inequalities are derived for k-Riemann-Liouville fractional integrals by using the definitions of different types of convex functions such as s-convex function, m-convex function, (s,m)-convex function and twice differentiable geometric-arithmetically s-convex function. Our results generalize the results of [8] and [18].