We report on the development of a novel active heat sink (AHS) for cooling of high-power electronic chips in inverters for hybrid electric vehicles (HEV) and plug-in HEV (PHEV). AHS employs convective heat transfer in liquid metal circulating in a miniature closed and sealed flow loop. The liquid metal removes high-flux waste heat from the chips and transfers it at a much reduced flux to engine coolant. Alternatively, AHS may be used to interface inverter electronics to an air-cooled heat exchanger (HEX). As a result, the presently used dedicated liquid coolant loop for thermal management of the inverter can be eliminated and the inverter sub-system can be greatly simplified. High flow velocity, good flow attachment, and relatively high thermal conductivity of liquid metal offer ultra-high heat transfer rates. Liquid metal flow can be maintained electromagnetically without any moving parts. Depending on the configuration, AHS thermal resistance can be around 0.1°C/W. This paper presents an update on the AHS development including model predictions and data from concept validation testing.