Two solvated cobalt(ii) terpyridine complexes, [Co(MeO-terpy)2](BF4)2·H2O (·H2O) and [Co(MeO-terpy)2](BF4)2·acetone (·acetone) were prepared. Annealing each of these complexes resulted in the formation of two desolvated species, and , respectively. ·H2O and exhibited two-step and gradual SCO. The compound ·acetone has high-spin at all temperatures and undergoes a reverse spin transition due to a phase change.