AbstractRecently, printing ink ingredients have been provided from vegetable oils as a renewable, non-toxic, and biodegradable resource. In this work, to produce bio-based polymer potentially exploitable in printing ink vehicles, tris(ethylenediamine)nickel(II) nitrate and bis(ethylenediamine)copper(II) nitrate complexes were synthesized, characterized, and then used as heterogeneous catalysts for polymerization of soybean oil. Also, nickel and copper oxide catalysts were fabricated through thermolysis of the mentioned complexes and, after characterization, were employed for the polymerization reaction. The results showed that the presence of nickel and copper complex catalysts favored the reaction progress as the viscosity of the reaction product was increased 4 and 1.3 times, respectively, compared with polymerization without a catalyst. Also, the results obtained from using nickel and copper oxides indicated that these metal oxides do not have a significant effect on the reaction process.