A thin uniform transparent film composed of the nonionic surfactant Triton X-100 and of poly(vinylmethylether), MW congruent to 30.000, has been deposited on a glass slide by dip-coating in a solution of reversed micelles in cyclohexane containing titanium(IV) tetraisopropoxide. Partial hydrolysis of the alkoxide assists in the attachment on the glass surface. Pyrene introduced in the film by original solubilization in cyclohexane forms diffusion-controlled excimers which can be switched on and off by changing the temperature. The pyrene-loaded film can be used as an optical oxygen sensor.