This research evaluates the addition of graphene sheets and hybrid nano-materials (graphene with different nano-materials like nano-silica or nano-clay) on compressive strength, flexural strength and thermal conductivity of cement mortar. Graphene sheets were added in three percentages (0.04%, 0.05%, and 0.06%) and (0.03%, 0.04%, and 0.05%) graphene sheets with 1%nano-silica or with 5% nano-clay by weight of cementitious materials. For all specimens, w/c ratio 0.4was applied. Scanning Electron Microscope and thermal conductivity tests were also performed on the optimum specimens at age 28 days. Results indicated that the optimum dose of graphene sheets was 0.05% by weight where the compressive strength, the flexural strength were improved by 35.66% and 33.33% respectively, and low thermal conductivity by 6.36% at age 28 days .No significant increase in compressive and flexural strength on adding hybrid nano-materials (graphene sheets with 1%nano- silica) to mortar. Also reduction effect in compressive and flexural strengths was achieved on adding hybrid nano-materials (graphene sheets with 5% nano-clay) to mortar. High thermal conductivity was obtained at age 28 days with respect to control ones when hybrid nano-materials were added to cement mortar.