One of the meat products in East Nusa Tenggara is called “se’i”, commonly made from beef, pork, deer meat, and recently have been developed using fish meat. Moisture Sorption Isotherm (MSI) is an important characteristic of food which is almost affected to aspect of the dehydration process and storage stability of the dried product. The aims of this study are to produce tuna se’i using liquid smoke with different concentrations, and to determine the MSIs using a constant relative humidity camber. In this method, water content of samples are allowed to equilibrate in a closed chamber with a salt solution which produces a desired relative humidity. Tuna se’i were made from two part of the tuna meat, that is, dorsal and belly. Five liquid smoke concentrations were used to dip the meats, that is, 1.0, 1.2, 1.4, 1.6 and 1.8%. The results show higher water conten in se’i from dorsal and the lower in se’i made from belly. The equilibrium moisture conents for samples in lower RHs ( 54%) ranged between 11.12 and 75.65% (db). Using five models equations, Oswin models shown best fit values of regression coefficients, with ranges value of relatife determination, 4.81 to 9.89, and MSI curves were sigmoid. From the MSI curves, can be conclude that tuna se’i need a packaging for storage in ambient temperature specially RHs above 50%. Key words: Liquid smoke, se’i, moisture sorption isotherm (MSI), equilibrium moisture content.