A new kind of fluorescent hyperbranched polymers was prepared by an end-capping approach, i.e., the hyperbranched poly(hydroxyl ether) was end capped with p-N, N-dimethylaminobenzaldehyde. The resulting polymers fluoresce yellow-green in solid and in solution. The maximum excitation and emission wavelengths in ethanol are 310 +/- 10 and 360 +/- 10 nm, respectively. Hyperbranched polyethers with various densities of chromophore groups showed different fluorescence intensities at the same concentration of chromophore groups. The fluorescent hyperbranched polyether with a high density of chromophore groups can form intramolecular excimers. The fluorescence signal of the resulting polymer increases with pH and passes through a maximum at 7.2-8.5 and then decreases gradually. Furthermore, the peak at 360 nm shifts to 405 nm with increasing pH. The fluorescence can be quenched by transition metal cations-such as Cu2+ and Fe3+, while the alkali and alkaline earth metal cations and Ni2+ and Co2+ have little effect on the fluorescence intensity. (C) 2003 Published by Elsevier B.V.