The purpose of this paper is to examine the class of functional integral equations of fractional order in the space of continuous functions on interval [0, a]. Using Darbo's fixed point theorem associated with the measure of noncompactness, we present sufficient conditions for existence of nondecreasing solutions of some functional integral equations of fractional order. These existence results include several obtained from previous studies. Finally, we establish some examples to show that our results are applicable. (C) 2015 All rights reserved.