There are several types of chromogenism, thermochromism (the material reversibly changes its optical properties when different temperatures, between 350 and 1175 °C, are applied), electrochromism (the material reversibly changes its optical properties when exposed to an electrical impulse in the form of current or potential) and photochromism, which is when a material has its color reversibly changed by exposure to electromagnetic light, that is, the reversible color change arises due to the occurrence of a chemical transformation between two chemical compounds, TiO₂ and WO₃, with different absorption spectra, between 400-700 nm, which are excited when exposed to electromagnetic radiation, usually UV, i.e., the photochromic effect reversibly changes the color of the material/sample; when this material is not being exposed to electromagnetic radiation, it returns to its original color, i.e., the color it had before being subjected to electromagnetic radiation. Some transition metal oxides, such as MoO₃, WO₃, TiO₂, V₂O₅ and Nb₂O₅, have been used in photochromic analysis. Two types of equipment are used in the analysis of photochromism: colorimeters and spectrophotometers, associated with an existing color system (RGB, Munsell, CIELab, etc). In this work, we analyze the synergism between the optical and photocatalytic properties of films, synthesized by spin-coater, of TiO₂ and TiO₂ mixed with a tungsten precursor (H₂WO₄). Photochromism was analyzed using a Konica-Minolta spectrophotometer, CM 2600 d, associated with the CIELab system. The results show that all samples had their color changed and, at the same time, the 20 ppm solution of methyl orange dye, at a concentration of 125 mL, was discolored during the time of exposure to UV radiation. That is, as the analysis time (15 minutes) passes, the methyl orange solution discolors by the photocatalytic action of the semiconductor films, which absorb UV light. These results were possible due to the synchronicity existing between the chemical and physical properties of TiO₂ and WO₃ which express variations between the different colors. This is a consequence of electrons being transferred in opposite directions, which allows an efficient separation between charges, and inhibits the recombination of the electron/hole pair and contributes to the formation of O₂ vacancies.