A high-voltage dc-dc converter with low voltage stress on the switches and output current tripler is presented in this paper. This converter exhibits three distinct features. First, the voltage stress on the switches is only one-third of the input voltage, so that switches of low voltage rating and thus of low on-resistance can be used. This can reduce the conduction loss. Second, all switches are soft-switched, so that the switching loss can be reduced. Third, the output circuit is a current tripler, so that the output current capacity and thus the power handling capacity of the converter are increased. A 4.8kW, 1000V/48V dc-dc converter prototype has been built and tested. Experimental results are favorably compared with theoretical predictions.