Chicken skin can be processed optimally into high economic value products such as gelatin because of the collagen content in it. The collagen molecule structure can be hydrolyzed using hydrochloric acid. This study was conducted to determine the effect of variations in the concentration of hydrochloric acid on chicken skin gelatin on pH, viscosity, and gel strength. The material used was Cobb strain chicken skin, hydrochloric acid, aquades. The study used a Completely Randomized Design (CRD) with five treatments of hydrochloric acid concentrations (2%, 3%, 4%, 5%, and 6%) and four repetitions. The data obtained were analyzed using a variance test and to find out the differences between treatments the Duncan Multiple Range Test was performed. Then, to find out the relationship pattern, it was analyzed using Orthogonal Polynomial. The results showed that the use of hydrochloric acid concentration had no significant effect (P> 0.05) on pH, viscosity, and gel strength. The optimum gelatin quality in the treatment of 2% hydrochloric acid concentration (pH 4,13; viscosity 1,403; and gel strength 11,795 g Bloom). The relationship between treatment and response to pH follows the linear regression equation Y = 0.2223x + 3,719, the strength of the gel follows the linear regression equation Y= -0,2479x + 3.8807.