A thermal printhead incorporating an elongated heat conduction chamber which is oriented in alignment with an array of printhead heating elements and used to transfer heat along the array to equalize heat distribution. The chamber contains a heat transfer fluid and wicks. The fluid when in a liquid state absorbs heat at a hot spot along the array through evaporation, transports the heat along the array to cooler portions of the chamber as a gas through gas dynamics and localized pressure, condenses to the liquid form, and returns to the hot spot through the capillary action of the wicks. In another embodiment, a metal strip is used to distribute the heat along the heating element array between hot and cool portions of the array.