Singularities are considered in the solution of the laminar bound- ary - layer equation at a position of separation. The works of Howarth (1938). Goldstein (1948), Stewartson (1958), Terrill (1960) and Akin- relere [(1981), (1982)] are reviewed to fully establish the existence of singularity in the incompressible boundary layer at separation for both the velocity and thermal fields. A ow at a large Reynold's number along an immersed solid surface around which bounda y layer is formed through which the velocity rises rapidly from zero at the surface to its value in the main stream is considered. It is found that whenever sep- aration does occur, the boundary layer equations cease to be valid on the upstream side and also down-stream of separation. In this paper, the works of Akinrelere [(1981),(1982)] on the thermal field had been extended to include suction through a porous surface. Following Stewartson (1958) the stream function 1 is expanded in a series of the type are non-dimensional dis- tances measured from the separation point. Analytical so1utions for f1; f2; f3; gl; g2 and g3 are presented. Results are obtained both for arbitrary Prandtl number and = 1, with and without suction.