In this study, the thermal and structural changes were observed in polyvinylchloride / graphene oxide (PVC/GO) composites in different amounts of 0.1, 0.3, 0.5 and 1 wt.%. To this aim, GO was prepared from natural graphite by Hummers method. XRD results of GO indicated that the interlayer distance increased from 0.33 nm to 0.88 nm. Energy Dispersive Spectroscopy (EDS) analysis results showed that oxygen content increased from 22.59 % to 47.95 % after the oxidation process. These features suggested that the GO sample, mainly oxygen-containing functional groups, was oxidized. PVC/GO composites were prepared by colloidal blending. XRD results of all composites indicated the GO layers well-dispersed in polymer matrix. SEM analysis revealed that the composites with 0.1 and 0.5 wt. % GO filler exhibited a uniform composite with highly porous and micro porous morphology respectively. TGA and DSC analysis showed that the use of minimum amount of GO in PVC matrix did not provide an important improvement on the thermal stability of the examined composites.