A new class of colored heterometallic ZnxTiyOw-zNz waveguides developed using a nanocolloidal sol-gel route combined with thermal treatment under ammonia atmosphere is reported. The resulting mesoporous layers are photostable and degrade the cationic pigment methylene blue under visible light irradiation. Semiconductor photocatalysis is currently being explored in environmental sciences, solar cell technologies, and preparative "green" technology.