This paper presents a voltage regulated step up Marx DC-DC converter suitable for HVDC offshore wind farm applications. This configuration has the capability to generate a variable high voltage adding controllability to the standard Marx converter with a fixed gain. For voltage control, an auxiliary controlled buck-boost converter was combined with the Marx converter to regulate the output voltage. The studies were carried out by simulating the converter with the design specifications of 6kV to 30kV voltage on LV and HV sides and 5MW rated power. The simulation results showed good voltage stability on the output DC line when the converter input voltage varies.