This article presents a simple ionic liquid-assisted solvothermal synthesis approach to the preparation of Ni particles from nickel acetylacetonate (Ni(acac) 2 ) as the precursor and N,Ndimethylformamide (DMF) as the solvent, where the ionic liquid, 1-methyl-3-ethoxyl imidazolium tetrafluoroborate ([C 2 OHmim]BF 4 ), was used as the reducing agent and as stabilizer. The as-prepared Ni particles were characterized by means of X-ray diffracion (XRD) and scanning electron microscopy (SEM). The formation mechanism of the Ni particles during the solvothermal process is discussed. The electrocatalytic effect of Ni particles for calcium dobesilate (calcium 2,5-dihydroxybenzenesulfonate, abridged as CDBS) oxidation on glassy carbon (GC) electrodes was investigated using cyclic voltammetry. It was found that the size of the Ni particles could be tuned by properly adjusting the concentration of the ionic liquid [C 2 OHmim]BF 4 and of the reaction time and temperature. Moreover, the Ni particles prepared after reaction at 180 • C for 6 h in the presence of the ionic liquid had a strong electrocatalytic effect on CDBS oxidation, making them potentially applicable in electrochemical biosensors.