This research investigates the effect of using multi-walled carbon nanotube (MWCNT) on flexural and compressive strengths, ultimate displacement and energy absorption capability of standard cement mortar. Different weight percentages of nanotubes as well as different dispersion methods were studied. The key issue of adding nanotubes to the composites is their proper dispersion, which was considered by comparing the results of two different dispersion methods. According to the test results and SEM images, the method using functionalized MWCNTs in combination with ultrasonication was pointed out as an appropriate dispersion method. Using nanotubes resulted in a significant increase in the flexural strength and energy absorption capability of cement mortar that represents the ability of properly dispersed nanotubes in bridging and closure of the micro cracks.