We demonstrate the suitability of multicomponent germanium oxide (GeO(2))-based glasses for engineering on-line chemical sensors operating in the 2-5 mu m spectral region. Bulk glass samples based on the oxide and oxy-fluoride multicomponent compositions GeO(2)-PbO-Na(2)O, GeO(2)-PbO-Na(2)O-Ga(2)O(3), and GeO(2)-PbO-Na(2)O-Ga(2)O(3)-PbF(2), respectively were analyzed for comparing thermal, structural, and optical properties. These glasses were melted using in an oxygen-rich atmosphere above 1200 degrees C, and annealed after casting before undertaking detailed thermal analysis. Glass compositions with especially high fluoride and lead concentrations are reported to have the glass transition temperature above 350 degrees C, which makes them suitable for operation in the 150 degrees-200 degrees C temperature range for chemical sensing and process metrology. The effects of composition on the thermal, structural, and optical properties of these glasses are studied using differential thermal analysis, Raman and infrared reflection spectroscopy, and prism coupling techniques. The compositional and wavelength dependence of refractive indices are also analyzed from which the value of the zero dispersion wavelength was determined.