Hydrogen as an alternative green fuel for depleting fossil fuels has been considered for a long time now. In this regard pristine metal nanoparticles and metal decorated nano materials have been attracting huge attention as electrocatalysts on modified electrodes for hydrogen evolution reaction (HER). Among various electrodes carbon paste electrode (CPE) are considered due to the inherent advantage of chemical stability and ease of fabrication. In the current study functionalized carbon nano tubes (f-CNTs) decorated with ruthenium (Ru) metal were synthesized in a green synthesis using microwave accelerating system and used to fabricate CPEs. These were studied for their electrocatalytic activity of HER. This was compared with bare CPE, and CPE modified with CNTs and f-CNTs in 0.5 M H2SO4. Voltammetric behaviour shows that the material displays better electro-catalytic activity by minimizing over potential and increasing reduction current. The tafel slope value of 100 mV/dec and 180 mV/dec indicates Volmer step to be the rate determining step. Also the material gave a very low onset potential of -0.23 V when compared with that of -0.8 V by bare CPE. The work indicates the electrocatalytic ability of Ru-CNTs of HER at a low loading level of 8.75%. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.