We study the surfaces of SAMs using an MD simulation dataset obtained from recent work of Kelkar and co-workers. The SAM structures are built from a planar array of alkanethiol ligands with hydroxyl, amine, or amide end groups. Each simulation consists of a single SAM solvated by bulk water. A simulation snapshot can be found in Figure . A total of 50 different SAMs were created (22 having hydroxyl groups, 14 with amine end groups, and 14 with amide end groups). The partial charges of the end groups are modulated using a scaling factor that simulates changes in the polarity of the SAM surface. Additional details on the MD simulation methodology and parameters are available in the work of work of Kelkar and co-workers. Our goal is to study the topology of water in a thin interfacial layer located at the SAM surface. To do so, we leverage the topological structures formed by water at the SAMwater interface to directly predict the hydration free energy (HFE) of the SAM through linear regression. The HFE is a property that captures surface hydrophobicity behavior and is key in understanding protein adsorption. A common method for computing the HFE in molecular simulations is indirect umbrella sampling (INDUS). This method is accurate but it is computationally expensive, as it requires sampling of a low-probability event. The dataset developed in previous work leveraged INDUS to create a set of SAM simulations with computed HFE values. Such simulations were used to train and test a CNN that directly predicts HFE from the SAM interfacial water structure (represented as a 2D water density field). Here, we instead develop a linear regression model using the EC of the SAM interfacial water structure.