The synthesis of four new complexes based on tridentate bispyrazole ligand by coordination of 4-[bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-amino]phenol with different transition metals such as Cu(NO3)2, NiCl2, CoCl2 and Cu(BF4)2 was reported. Their characterization by means of IR, UV–visible and mass spectroscopy was investigated. Their optical pollutant gases recognition capabilities as solid state thin layer on quartz were investigated. Different analytes have been studied such as SO2, NO2, CO, CH4 and NH3. The coordinated complex layer presents reversible system sensitivity towards SO2 and NO2 with good sequences in function with time. No influence on the optical properties was shown in the presence of CO, CH4 and NH3.Research highlights▶ Synthesis of 4-[bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-amino]phenol complexes with tranistion metals. ▶ Thin films preparation and optical characterization. ▶ Test in controlled athmosphere as optical gas senging towards SO2, NO2, CO, CH4 and NH3.