Heavy condensate or oil can contain significant amounts of mercury which causes marketing, processing and environmental concerns. We have developed an effective process to remove all kinds of mercury compounds in heavy condensate. At the conditions tested, the total mercury content in a condensate was reduced from 3,000 to 10 ppb, representing 99.7% mercury removal. In the process, the condensate is pumped upflow through a reactor filled with activated carbon and polysulfide solution at mild conditions. The effluent is a clear, low mercury product. The theory and principles of the process are developed and verified with experiments. Process variables were also explored to define the preferred region of operation.