Wetting and spreading in high temperature reactive metal-metal systems is of significant importance in many joining processes. An overview of reactive wetting is presented outlining the principal differences between inert and reactive wetting. New experimental evidence is presented that identifies an early time regime in reactive wetting in which spreading occurs without macroscopic morphological change of the solid-liquid interface. This regime precedes the heavily studied reactive wetting regime. Additional new experimental evidence is presented of kinetic roughening in a high temperature reactive system. Quantitative characterization of this roughening reveals similarities with room temperature systems. These new data provide evidence that supports the existence of several sequential time regimes in the reactive wetting process in which different physicochemical phenomena are dominant.