Palladium (Pd) composite nanoparticles (NPs) supported on multi-walled carbon nanotubes (MWCNTs) (denoted as Pd/MWCNTs) are fabricated by a very simple process of hydrothermal reaction (HR) using the technical grade PdO as the precursor. With a HR period of 3 h, the Pd NPs with an average size of ～5.0 nm are found to be quite uniformly dispersed on the surface of MWCNTs. The electrocatalytic activity towards ethanol oxidation reaction (EOR) for the synthesized catalysts is probed by using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The 3-h prepared catalyst has demonstrated 6.7 times better EOR activity than 5-h prepared sample (159.7 mA mg?1 vs. 23.8 mA mg?1) at an applied potential of ?0.24 V (vs. SCE) in the CA test. The excellent electrocatalytic activity of the 3-h Pd/MWCNTs catalyst toward EOR is mainly ascribed to its easier hydrogen evolution, lower electrode potential and the existence of PdO as compared to other catalysts prepared.