Hydrophobic deep eutectic solvents (HDESs) are considered versatile designer solvents, characterized by a broad range of hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs).The selection of appropriate HBDs plays a pivotal role in determining the properties of HDESs.In this work, we propose a model for screening or narrowing the range of suitable HBD reagents to enhance the extraction efficiency of metal ions and organic compoundsThis model utilizes surface tension (γt) or refractive index (nD) as the key parameters for selecting HBDs.The extraction efficiency of metal ions or organic compounds is observed to increase with a decrease in the surface tension or refractive index of the HBDs, as demonstrated in 16 different HDES systems reported in the literature, thereby confirming the reliability of the proposed method.Notably, in contrast to the COSMO-RS model, which necessitates detailed at.-level information about the pure compounds, the surface tension (γt) or refractive index (nD) model (referred to as the SA/RI model) simplifies the process by screening or narrowing the selection of HBDs based solely on these two parameters.Furthermore, by performing linear regression on γt and nD data for 31 HBDs from the literature, we establish the equation γt-(n2D-1)/(2n2D+1), which serves as a reliable tool for assessing the validity of γt and nD values for HBDs.This equation contributes to a deeper understanding of the physicochem. properties of HBDs, facilitating more effective solvent design.