In order to form a uniform oxidation layer and spinel crystalline phase that was supposed to help strong bonding in Kovar(Fe-29Ni-17Co)to-glass sealing the humidified nitrogen (2.3%H2O/N2) was used as an oxidation atmosphere. Kovar oxidation was diffusion-contolled and the activation energy was 2.51 kcal/mol at 600-900$^{circ}C$ After oxidation at 600$^{circ}C$ the oxidation layer was under 1$mu extrm{m}$ thickness and crystalline phase was spinel which was found to be suitable for the Kovar-to-glass sealing.