In this paper a complete solution (initiation to completion) for the sub-critical spatially homogeneous reaction has been developed. Complete reaction consumption is included. The solution is in two parts: (1) the rapid temperature rise (2) the subsequent decay back to initial conditions. The two parts are joined using the method of matched asymptotic expansions. The complete temperature-time history is displayed graphically, to show the dependence of the temperature variation and fuel consumption on reaction order, heat loss parameter and the thermodynamic properties of the system.