The　surface　of　agglomerated　nanodiamond　(ND)　particles　was　modified　with　carboxylic　acid　and　ammine　moieties　using　UV/ozone　and　ball　milling　methods　respectively.　The　microstructural　analysis　revealed　that　the　initial　agglomerated　NDs　clusters　were　predominantly　reduced　in　size　with　the　UV/ozone　and　ball　milling　treatments.　The　UV/ozone　and　ball　mill　functionalized　NDs　were　kept　for　dispersion　under　observations　into　ethanol,　water　and　dimethyl　sulfonic　oxide　(DMSO)　solvents.　The　dispersion　images　satisfactorily　showed　that　all　the　surface　modified　NDs　samples　reveals　good　dispersion　tendency　comparatively　to　pristine　NDs　whereas,　the　ball　mill　treated　NDs　showed　outstanding　dispersion　behavior　rather　than　all　samples.　Furthermore,　the　mechanical　properties　were　investigated　using　various　amounts　of　surface　modified　NDs　in　epoxy　matrix.　The　mechanical　properties　were　checked　in　terms　of　ultimate　tensile　strength　(UTS),　Percent　break　strain　and　Flexural　strength.　The　results　of　all　the　mentioned　mechanical　properties　revealed　that　0.3　wt%　was　the　optimum　amount　for　getting　highest　properties.　Similarly　ball　mill　treated　NDs　represented　the　remarkable　enhancements　in　all　mechanical　performances　comparatively　to　pristine　and　UV/ozone　treated　ND　samples.　©　2020　Elsevier　B.V.