The aim of the test was to determine the effect of natural zeolite clinoptilolite as a filler in paper onto stability of UV termochromic color. Laboratory sheets were prepared by adding 20% of filler (calcium carbonate and zeolite). Natural zeolite was added to the calcium carbonate in various proportions by weight (20 to 60%). Laboratory sheets have been prepared in accordance with ISO 5269-1. To create prints, the laboratory device IGT A2 was used. The samples were subjected to artificial aging process in chamber aging Suntest XLS + at various intervals for 40 hours. (E, a *, b *, c *, L *) changes depending on the time of accelerated aging are very large, about after 1 hour. The smallest (E, a *, b *, c *, L *) changes are expected in the sample with 20% clinoptilolite, and the largest in the sample with 60% clinoptilolite. Clinoptilolite as filler has beneficial effect on the UV stability of termochromic colors in lower concentrations, and higher concentrations likely to come to the fore oxidation properties of Fe-oxides present in the sample of natural zeolite.