Determination of the pH has critical importance for a wide range of applications, namely in the medical and environmental fields. Optical pH sensors (small and simple device) are suitable for remote monitoring in hazardous environments and insensitive to electromagnetic interferences. The main disadvantage of optic pH sensors is narrow dynamic range. The use of several indicators can overcome this problem but requires special data processing. The sol-gel technology was used for preparation thin films with immobilized two pH-indicators (pyrocatechol violet and bromophenol blue) at the surface of glass plates. The UV-Vis spectrum of the films with indicators for number of buffers solutions (pH 1.0–8.0) and standard samples were obtained. It has been shown that detection of the analytical signal (absorbance) at one wavelength does not give unique solution about pH value. The possibility of using multidimensional data was investigated and the multifactor analysis was used. To evaluate the precision and the predictive capabilities of the model, the errors of calibration (RMSEC) and prediction (RMSEP) were calculated. Cross validation for calibration models was used.