[en] The nuclear technique using radioisotope as a tracer in oil industry has assisted to solve the degradation of oil production. Usually, the degradation of oil production in well caused by the formation changing of hydrostatic pressure of the oil layer in the well. This problem could be evaluated by injection of water to oil well, for recovering this hydrostatic pressure. The watcher of the water injection success is done by the way of nuclear technique radioactive tracer systems, applied radioisotope having short half life and low gamma radiation energy. Radioisotope cobalt-58 in the complex form with naphthenate ( ⁵⁸Co-naphthenate ) often used as the tracer in the water injection technique. The tracer ⁵⁸Co-naphthenate relatively easy to synthesis and radioisotope ⁵⁸Co has half life 70.86 days and gamma energy was 0.811 Me v. The synthesis method of ⁵⁸Co-naphthenate route has been carried out by mixing of ⁵⁸CoCl₂ radioisotope solution with sodium naphthenate (C₅H₉CH₂COONa) in the optimum condition. The results shows that the optimal mole ratio of cobalt-58 and naphthenate was 1:6 which produced 87,38 % of ren dement and 82,5 % of efficiency labelling. This synthesis technique was made permanent procedure for making of ⁵⁸Co-naphthenate complex as radioactive tracer in service of radioisotope production especially industrial area. (author)