This paper presents the characterization of a resistive high-voltage dc (HVDC) reference divider and methods to establish traceability. The divider is designed for use as a laboratory reference for calibration of HVDC measuring systems up to 1000 kV. Targeting a measurement uncertainty of 20 μV/V at full voltage has put a focus on the temperature coefficients of the resistors, elimination of humidity dependence, and control of leakage currents in the high-voltage arm. A scale factor calibration against a 50 kV divider at 10 kV leads to an expanded uncertainty of 15 μV/V.