A technique to generate a pulsed high-current ablation arc jet was developed for the purpose of establishing a method to spray materials in the velocity range exceeding the limit of conventional thermal spraying. Basic structure of the arc jet generator was similar to that of the electromagnetic railgun except that the arc discharge was taking place through array of spot electrodes exposing on an insulating bore wall. Preliminary experiments were conducted using tungsten spot electrodes and fiber reinforced plastic (FRP) bore. By supplying a pulsed high current of 120kA in peak, an arc jet of 2-5km/s in exit velocity and 20MPa in peak bore pressure was generated. During the jet generation, about 0.6g of tungsten was ablated from the spot electrodes and sprayed to a steel substrate. However, the coating did not contain metallic tungsten but mainly consisted of tungsten carbide (W₂C), of which the carbon was considered to be supplied by ablation of the FRP wall. This result indicated that the choice of the insulating materials would be essential for controlling the composition of the coating. Two unique features were observed in the coating-substrate boundary, that is, a diffusion of both tungsten and iron and an irregular ripples of the boundary layer. Those features suggested that the coating process involved both intensive heating and hydrodynamic deformation of the substrate surface due to either a high heat flux from the arc jet or high-velocity collision of the particles.