Organic dyes immobilized nanocrystalline anatase matrix is synthesized by low-temperature sol-gel method for sensing analysis. It is determined that the thermally stable anatase phase has average crystallite size of 5 nm, low roughness 2 nm, average particle size 5.3 nm, specific surface area of 170 m2g–1 and refractive index 2. However, after immobilization, smaller average crystallite size ∼3 nm, high roughness 9 nm, smaller average particle size 4.5 nm, larger surface area of 196 m2g–1 and low refractive index 1.8 is determined. The sensitivity 116 RI/pH at 428 nm over pH 1–12 is calculated. The average response time ∼0.3 s in pH 12 is observed
