Apparatus and method for thermally controlled processing of microelectronic workpieces with liquids. An apparatus in accordance with and embodiment of the invention includes a process vessel configured to carry a processing liquid, such as an electroless processing liquid. The vessel has a thermally transmissive wall for transferring heat to and/or from the processing liquid within. A heat transfer device, such as a reservoir that receives processing liquid spilling over from the process vessel, transfers heat to or from the processing liquid within the process vessel. The heat transfer device can also transfer heat to or from an internal or external heat source, such as a conduit carrying a heat transfer fluid, or an electrical resistance heater. The interaction between the microelectronic workpiece and the processing liquid can be further controlled by controlling the rate at which the microelectronic workpiece rotates and/or the manner in which the microelectronic workpiece is introduced to and/or withdrawn from the processing liquid.