We investigated the structural and magnetic properties of Co2MnSi deposited on Co90Fe10 and Co50Fe50 ferromagnetic seed-layers at room temperature before and after annealing at various temperatures up to 500 degrees C. The lattice misfits between Co2MnSi and Co90Fe10 and between Co2MnSi and Co50Fe50 were expected to be 2.0% and 0.5%, respectively, which are small enough to allow an epitaxial relation or to promote a texture between layers. The Co2MnSi grown on the Co90Fe10 seed-layer transformed from an A2 to a B2 structure when it was annealed at a temperature as low as 350 degrees C, evidenced by the (200) peak. The transformation of the Co2MnSi to an L2(1) structure did not take place until it was annealed at 500 degrees C. The soft magnetic properties of the Co2MnSi on the Co90Fe10 were substantially improved. In contrast, the Co2MnSi prepared on the Co90Fe10 seed-layer did not transform to L2(1) even after annealing at 500 degrees C. Instead, it showed a B2 structure. The Co90Fe10 and CosoFeso ferromagnetic seed-layers found to be useful not only to facilitate the transformation to ordered phases but to improve the soft magnetism of Co2MnSi, which makes feasible for the use of Co2MnSi in applications such as magnetic read heads, magnetic random access memories, and spin transistors. (C) 2012 Elsevier B.V. All rights reserved.