  In this paper, we introduce the notion of strongly {\varphi}-convex functions
with respect to c>0 and present some properties and representation of such
functions. We obtain a characterization of inner product spaces involving the
notion of strongly {\varphi}-convex functions. Finaly, a version of Hermite
Hadamard-type inequalities for strongly {\varphi}-convex functions are
established.
