In this article we will discuss the solubility test of cellulose propionate on various ratio variations of aqua destillata–acetone. Previously cellulose propionate was dispersed into a solvent mixture of aqua destillata-acetone. Variation in volume ratio of aqua destillata–acetone was 4: 1; 3: 1; 2: 1; 1: 2; 1: 3, and 1: 4. The mixture is stirred for 48 h and filtered. The solid was then put into a mold with a sintering technique at a temperature of 100oC for 5-10 minutes. Membrane characterization includes solubility parameters (δmix), density using picno meter and calculation of sample dimensions, and swelling index. The results of the calculation of solubility parameters (δmix) solvent mixture of aqua destillata–acetone (1: 4) close to δ cellulose acetate (12.47). Differences in membrane density using picno meter and calculations in dimensions indicate the presence of cavities or pores in the membrane. Difference in density value of both calculations occurs in the membrane with a mixture of aqua destillata–acetone (1: 3). The highest hydrophobicity properties were obtained in the ratio of solvents of destillata–acetone (1: 4) with the smallest swelling index (48.14%).