A method for electroless plating of a substrate is provided that comprises exposing an electroless plating reagent comprising a metal to be plated and at least one reducing agent to a solid phase Activation Material to form an activated electroless plating reagent prior to application of the electroless plating reagent to the substrate. The activated electroless plating reagent is applied to a substrate in the process chamber under conditions to cause the metal of the electroless plating reagent to deposit on the substrate. Systems and modules are also described.