Distillers dried grains with solubles (DDGS) is one of the coproducts obtained from dry-grind ethanol manufacturing. As the ethanol industry is growing exponentially, the production of DDGS has been significantly increasing as well. To optimize the use of DDGS, it has to be economically transported from one part of the country to other parts, and stored efficiently. But DDGS has some flow issues, which often makes storage and transportation very problematic. So the objective of this study was to investigate the dynamic water adsorption characteristics of DDGS with four soluble levels at four temperatures and four relative humidities. Three mathematical models were then used to fit the adsorption data (Peleg, Pilosof, and Singh-Kulshrestha). As there was no model available for describing the water adsorption characteristics of DDGS with varying soluble levels at various temperature and relative humidity conditions, a new comprehensive model was developed. The new model, Ganesan-Rosentrater-Muthu (GRM) model, encompassed soluble level, temperature, and relative humidity effects, along with time and moisture content. The GRM model (R2 = 0.94; F =16503.90) provided a good description of DDGS water adsorption behavior and can be used to predict the dynamic adsorption of water in DDGS for a broad range of storage conditions.