Design of a soft-switching, current-mode controlled dc-dc converter for arc welding is described in the paper. The arc welder based on switch-mode dc-dc power supply utilises current-mode control for improving working performance of the current source. The switching power losses are decreased to minimum using non dissipative turn-off snubber. The operation and performance of the proposed dc current source was verified on the 3 kW laboratory model of the welder. High efficiency up to 90% is achieved at nominal current of 120A.@en