Titania nanoparticles in a hydroxypropyl cellulose matrix produced using a sol-gel method were utilized to prepare films on polycarbonate slides and coatings on cellulose papers. The exposure of these materials to hydrogen peroxide gas leads to the development of an intense yellow color. By using an inexpensive web camera and a tungsten lamp to measure the reflected light, first-order behavior in the color change was observed when exposed to peroxide vapor of less than 50 ppm. For 50 mass percent titania nanoparticles in hydroxypropyl cellulose films on polycarbonate, the detection limit was estimated to be 90 ppm after a 1 min measurement and 1.5 ppm after a 1 h integration. The coatings on the filter paper had a 3-fold higher sensitivity compared to the films, with a detection limit of 5.4 ppm peroxide for a 1 min measurement and 0.09 ppm peroxide for a 1 h integration. The high sensitivity and rapid response of these films make them a promising material for use as a sensitive peroxide detector.