Semi-interpenetrating chitosan (CS)/poly(ethylene glycol) (PEG) sponges were designed by crosslinking PEG in the CS matrix via nucleophilic thiol-yne addition. This reaction does not require the use of any potentially cytotoxic catalytic species and offers possibilities to prepare materials with tunable properties. The molecular structure of the sponges was analyzed by FTIR spectroscopy, which provided evidence of intermolecular interactions between PEG and CS, and the presence of a cross-linked PEG network in the CS matrix. The crosslinked CS/PEG sponges displayed a structure with large interconnected pores (tens of micrometers) as demonstrated by scanning electron miscoscopy, in comparison to blended materials with irregular and smaller pores. The crosslinked sponges also exhibited improved mechanical properties (higher Young's modulus) and stability at physiological pH. All together, these interesting properties open the way for the application of this biomaterial in topical drug delivery. © 2017 Elsevier Ltd