The objective of the research study was to determine the effect of acetylation of potato starch on binding water in starch gels produced. There were taken measurements of the spin-lattice T₁ and spin-spin T₂ relaxation times with the use of a low-field nuclear magnetic resonance (NMR); also, the water activity in acetylated starch gels was determined. A polymer with a known degree of substitution (DS) was utilized in the study. Those systems were measured where the content of starch ranged from 0.02 g/g to 0.10 g/g. The results of the water activity measured were used to determine the hydration coefficient of the starch defined as the weight of water associated with 1 g of biopolymer. It was found that the applied modification of starch caused the value of its hydration to decrease. The acetylated starch with a 0.06 degree of substitution was characterized by the lowest coefficient of hydration. On the basis of the relaxation time values, there were determined those parameters, which characterized the molecular dynamics of polymer hydrating water fraction. The determined spin-spin relaxation rate of hydration water molecules decreased with the increasing quantity of acetyl groups that exchanged hydroxyl groups. That fact means that the quantity of water molecules bound in the polymer network is reduced owing to the predominance of polymerpolymer interactions over the polymer-water interactions.