The investigation of size-reduction effects on the spin crossover properties of a class of transition metal complexes has recently become an area of intensive research. However, to avoid inter-particle interactions, ensemble averaging and matrix effects it is necessary to develop methods for the systematic study of individual nano-objects. To this aim thin films and nano-patterns of the compound [FeII(hptrz)3](OTs)2 doped with acridine orange were elaborated by spin coating and soft-lithography, respectively. The luminescence intensity was found to change significantly upon the spin transition even in isolated nano-objects of ca. 150 nm size, allowing us to monitor in a massively parallel way the spin crossover phenomenon in large arrays via fluorescence microscopy.