Polydiacetylene (PDA) shows a unique colorimetric response toward external stimuli, such as heat. Herein, self-assembled hydrogels were prepared by 10,12-tricosadiynoic acid (TCDA) and 1-oleoylglycerol (Monoolein, MO). The hydrogel of TCDA/MO (1/1) turned to blue by UV irradiation, and the color changed to red by heating. Although unpolymerized gel deformed within 3 h at 70 degrees C, the polymerized hydrogel maintained its structure at least for 4 h.This method successfully produced hydrogel materials including the organized membranes composed of PDA precursor molecules.