Copper (I) mediated Huisgen 1,3 dipolar cycloaddition of 4-(piperidine-1-yl)-N-(prop-1-yne- 3-yl)-1,8-naphtalimide (PN) to poly(αN3εCL-co-εCL) of three different molar ratio of αN3εCL was performed. Reaction was succesfull for poly(αN3εCL-co-εCL) with molar fraction of αN3εCL f = 0,22. No degradation of substituted PCL was observed during the synthetic path, therefore the PN molecule is suitable for click coupling to well defined polyester. New aliphatic polyester based on polycaprolactone was synthesized and characterized by means of 1 HNMR spectra and Gel permeation chromatography calibrated with polystyrene standards. The spectra of other two copolymers coupled with PN were not measured due to their low solubility in common organic solvents. Keywords: living polymerization, α-chloro-ε-caprolactone, click reaction