A selective spectrophotometric method has been developed for the determination of nickel(II) and cobalt(II) as their phenanthrenequinone monoximate into molten naphthalene. The naphthalene was allowed to solidify, separated by filtration, dried and dissolved in dimethylformamide. The solution was diluted to 10 ml and the absorbance measured at 460 nm for nickel and 470 nm for cobalt. In both cases, the solutions were stable for more than 18 h. Beer's law is obeyed over the concentration range of 1.2-10.6 μg of nickel and 0.6-7.8 μg of cobalt in 10 ml of dimethylformamide. The various factors such as pH, amounts of reagent and naphthalene, and shaking and standing times were studied. The interference of various ions has been examined in detail and the method were developed for the determination of nickel and cobalt in various alloys and also nickel in hydrogenated oils. Conditions were also developed for the simultaneous determination of nickel and cobalt in alloys.