The stress-strain-temperature relation in TiNi alloys was investigated from the phenomenological point of view. A set of constitutive equations consisting of the mechanical constitutive equation and of the transformation kinetics were presented to describe the transformation pseudoelasticity, the partial pseudoelasticity and the shape memory effect. The material constants in the theory were determined from the tension tests on TiNi wire specimens at various temperatures. The theory was successfully applied to the calculation of the recovery force induced in the heating process under the condition of constraint strain.