The title compound, a major animal feed supplement, abbreviated as HMTBA and alternatively called dl-me-thio-nine hy-droxy analogue, C5H10O3S, (I), was isolated in pure anhydrous monomeric form. The melting point is 302.5 K and the compound crystallizes in the monoclinic space group P21/c, with two conformationally non-equivalent mol-ecules [(I ) and (I )] in the asymmetric unit. The crystal structure is formed by alternating polar and non-polar layers running along the plane and features an extensive hydrogen-bonding network within the polar layers. The Hirshfeld surface analysis revealed a significant contribution of non-polar H⋯H and H⋯S inter-actions to the packing forces for both mol-ecules.