A chromophore terminated aliphatic polyether was obtained by polymer analogous conversion of the amino groups of Jeffamine (R) ED-600 with 4-[5-(4-acetoxy-phenyl)-3-oxo-penta-1,4-dienyl]benzoic acid and subsequent saponification of the acetoxy group. UV/Vis spectroscopic investigations showed that deprotonation of the chromophoric groups by organic or inorganic bases as for example poly(1,8-octamethyleneacetamidine) and NaOH, respectively, results in a distinct bathochromic shift of the chromophores longest wavelength absorption band by about 100 nm. This effect is discussed in terms of polymer blends where the covalently bound chromophore can act as optical probe for acid-base interactions between the components.