Porous modified collagens with vinyl groups were synthesized by reaction with 2,3-dimethylmaleic anhydride or citraconic anhydride. The structure of modified collagen was assessed by analytical determination of the amino groups in collagen and spectroscopic methods (Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (H-1 NMR)). The amount of protonated amino groups and carboxylic acid moieties of the samples have been determined by potentiometric titration. The dependence of the viscosity of diluted collagen solutions on the concentration and temperature was followed to determine their denaturation transitions. The increased average molecular weight, particle size, and second virial coefficient of modified collagen solutions with respect to the unmodified one proved that modification took place. Coupled thermal analyses (TG/DTG/DTA/FT-IR/MS) also indicated the collagen modification by increased thermal stability and new volatile compounds formed during decomposition. The adhesion tests revealed their potential application in wound dressing and tissue engineering.