Tilapia skin gelatins were extracted with optimal acetic or citric acid concentrations which provide similar optimum protein yield (22g/100 wet weight), and rheological properties of gelatin solutions with various concentrations were measured and characterized. Commercial valued properties including bloom strength, gelling and melting point, viscosity were measured to compare the samples of the two gelatins. Liner viscoelastic range (LVR) of gelatin preparations with increasing concentration and decreasing temperature were determined. Temperature sweep was conducted for comparison and characterization the relationships between concentration and gelling/melting point of gelatin extracted by citric acid or acetic acid. The results showed that the melting and gelling point varying with concentration followed exponential curve (R2 as high as 0.99), and there were rarely molecular fractions in extracted gelatins. Elastic modulus (GâČ) of gelatin gels was mainly a function of cold temperature and time, while the discrepancy between the melting behaviors of gelatin extracted by two acids may stem from the composition and molecular weight of gelatin chains. In conclusion, the tilapia skin gelatin extracted in our study is of high qualities and rheological analysis is a critical tool for material of gelatin differentiation from varied molecular properties.