Double network (DN) hydrogels have drawn considerable attention as innovative materials possessing both high water content as well as improved mechanical properties. In this study, DN hydrogels were formed from a combination of two hydrogel networks. The first network composed of acrylamide (AAm) and N’, N’-methylenebisacrylamide (MBAAm). AAm and MBAAm were covalently crosslinked via photopolymerization with/without the presence of the second network pre-gel mixture i.e physically crosslinked gelatin-calcium carbonate (GCa) or chitosan-alginic acid (CAA). The mechanical properties of the hydrogels revealed that tensile strength, Young’s modulus and elongation at break increased with increasing amount of second network component; i.e. GCa and CAA. These data could confirm that the DN hydrogels possessed ‘stretchability’ character. Overall, PAAm-GCa and PAAm-CAA DN hydrogels had shown better mechanical strength than the PAAm single network hydrogels. We foreseen that DN hydrogels are highly potential to be developed as artificial muscles.