Dissolution and gelation procedures have a great influence on gelation time, microstructure and mechanical properties of reconstituted collagen products. We have investigated the dissolution of atelocollagen in CO2/water solutions at low temperature (4 degrees C) at different CO2 pressures (0.3-0.9 MPa), as well as gelation kinetics and physico-chemical properties of the hydrogel obtained after CO2 removal. Compared to conventional methods, the CO2-assisted technique resulted in faster soluble collagen dissolution and faster gelation into transparent gels characterized by thin 10 nm fibrils. Electrophoresis and CD spectroscopy demonstrated that the process did not denature the soluble collagen. The possibility to obtain collagen dissolution and gelation without the use of chemical agent other than water and CO2 makes this process particularly appealing for biomedical applications.