Low Pt-loaded graphene nanocomposites were prepared using a two-step reduction process. Graphene dispersion was first prepared from graphene oxide using hydrazine hydrate as a reducing agent. Pt-reduced graphene oxide composites were then synthesized in the aqueous graphene dispersion at 90 degrees C without the need for another reductant. Pt/graphene composite films were then deposited on fluorine-doped tin oxide substrates using a simple drop-casting method at room temperature and subsequently used as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Cyclic voltammetry and electrical impedance analysis show that the composite electrodes have high electrocatalytic activity toward iodide/triiodide reduction. The energy conversion efficiency of the Pt/graphene CE-based DSSC was found to be 1.9 % lower than that of cells with a Pt-based CE.