The reaction of osmium(II) tetra-15-crown-5-porphyrin (Os(II)TCP) with molecular iodine in high yield yielded the corresponding osmium(IV) porphyrin containing iodide ions in the axial positions of the osmium(IV) atom and possessing paramagnetic properties according to 1H NMR. The iodine anions in the complex create an additional heavy atom effect in addition to such an effect from the osmium(IV) cation, which is of certain interest from the point of view of increasing the probability of phosphorescence transitions in osmium(IV) crown porphyrin molecules. The paramagnetism of osmium(IV) crown porphyrin also affects the probability of phosphorescence transitions, and this effect depends on temperature. These two effects (paramagnetism and the heavy atom effect) create some interest in terms of the possibility of creating a phosphorescent temperature sensor based on the new osmium(IV) crown porphyrin. A comparative analysis of the kinetics of phosphorescence decay of osmium(IV), osmium(VI) and osmium(II) porphyrins in the polystyrene matrix at temperatures of 298 and 77 K. It was found that the new osmium(IV) crown porphyrin has the highest phosphorescence lifetime with temperature in this series and can be considered as a luminescent temperature sensor for changes in phosphorescence lifetime.