Belinostat is a histone deacetylase inhibitor for the treatment of refractory T-cell lymphoma. Our study found that the tendency to form solvates of belinostat with hydrogen-bond acceptor type solvents was obvious based on the COSMO-RS model. Motivated by the prediction results, we investigated eight novel solvates, with 1,4-dioxane, tetrahydrofuran, furan, 3-picoline, cyclopentanone, 1-methyl-2-pyrrolidinone, and dimethyl sulfoxide/water as guest molecules, obtained by different crystallization methods. The obtained solid forms were thoroughly characterized with various analytical techniques, namely, powder X-ray diffraction, Fourier transform infrared spectroscopy, and thermal analysis. The thermal stability order of solvates was