The thermohalochromic behavior of Reichardt’s E T (30) betaine – the temperature-dependent variation of its halochromic band in the presence of a cation – was investigated for the first time in NaI solutions of HBD- (methanol, ethanol, 1-propanol, 1-butanol) and non-HBD-solvents (acetonitrile, dimethylformamide) at 15 and 55°C. The solvent-dependent thermohalochromism of the pyridinium-N-phenolate betaine dye was interpreted in terms of the effect of the temperature on the dye–cation association in solution.