In this study, triblock copolymers composed of PEG (polyethylene glycol) flanked by thermosensitive pHPMAmlac poly (N-(2-hydroxypropyl) methacrylamide lactate) blocks modified with methacrylate moieties are crosslinked by both physical and chemical methods to yield hydrogels with good mechanical properties and stability. These systems exhibit LCST (Lower Critical Solution Temperature) behaviour in aqueous solution, so they can be used as injectable in situ forming hydrogel. The excellent protein compatibility and the tunable structure of the polymer render these hydrogels highly promising materials for protein delivery.