Nickel-N,N'-bis(salicylidene)-o-phenylenediamine complex (nickel–salophen) was synthesized by a novel and simple solvothermal treatment of ethanolic solution of 1,2-phenylene diamine, salicylaldehyde and nickel chloride with molar ratio (1:2:1) for 4h in stainless steel autoclave 120 °C. The prepared Nickel- salophen complex was characterized by elemental analysis, 1H-NMR, FT-IR, mass spectroscopy, UV-Vis spectroscopy, magnetic properties and thermal analysis. The present approach proved its efficiency to produce pure nickel–salophen complex in high yield. Plus, It is noteworthy that a comparison of the chemical shifts of the ligand with its nickel complex indicates that the signals due to phenolic protons are absent in the complex 1H-NMR spectrum which can be attributed due to the deprotonation of the phenolic groups and subsequently the replacement of the protons by the metal.