Waste of Salicornia ramosissima a halophyte plant used in gourmet cuisine, can be valorized after being dried and milled, becoming a vegetable salt, a healthier replacer of kitchen salt due to its lower sodium content (around 10‐fold less) but still maintaining an intense salty taste. To study the shelf life of this vegetable salt from S. ramosissima, packed in a cylindrical aluminum box, an accelerated shelf‐life testing (ASLT) was first carried out at 35, 40, 45, and 50°C by monitoring color, moisture, and water activity (aw) throughout the storage period. Moisture and aw decreased at increasing temperature, but the color was not affected. The moisture sorption isotherms (MSIs) were next produced at 15, 25, 35, and 45°C and relative humidity (RH: 6.5%–80%) using the static gravimetric method. Several mathematical models were tested to fit the MSI experimental data and finally the Oswin model was used to predict the moisture content. With this model, the isosteric heat was determined. A mass–balance model was used to predict shelf life and the equilibrium moisture content (Me) during storage based on predetermined MSI and water vapor rate transmission (WVTR) data. The predicted shelf life of the package with and without adhesive tape around the lid was 35 and 80 days (25°C, 75% RH) and 19 and 63 days (35°C, 90% RH), respectively. Practical Applications By understanding the moisture sorption phenomenon in hygroscopic powders, this study can provide valuable data to the food industry dealing with such products. Being a microbiologically safe product due to its low aw and having color stabilized through previous drying, its mode of failure during storage proved to be the loss of its free‐flowing capacity. A methodology to evaluate the shelf life of this hygroscopic product packed in a cylindrical aluminum box is described. There is a need to draw attention to the fact that, despite aluminum with a thickness of .23 mm is a very effective barrier to water vapor penetration, such package has an extremely small gap between the lid and body, which is hard to measure, yet allows water vapor to flow through the package at a rate that results in its shelf life being less than 3 months. Ways to overcome this issue are suggested.