α-iron single crystals have been investigated in the so-called (112)  anti-twinning slip system between 123 and 296 K, up to 40 % deformation. Stress relaxation and creep tests have been used to measure activation parameters continuously during tensile straining. Berg-Barrett X-Ray reflection topography was used to examine the overall dislocation substructure. In agreement with a previous study on the (101)  slip system, we confirm the strong influence of lattice friction below about 200 K, despite the very different orientation conditions. In contrast, the strengthening behaviour found at higher temperatures is different, and there is a two stage stress-strain curve : stage I is clearly associated with homogeneous dislocation substructure, while in stage II it is definitely heterogeneous.