A series of substituted benzaldehyde hepta-O-acetyl-b-lactosyl thiosemicarbazones were synthesized by condensation reactions of hepta-O-acetyl-b-lactosyl thiosemicarbazide with corresponding substituted benzaldehydes in the presence of 2-hydroxyethylammonium acetate, [HOCH₂CH₂NH₃⁺]^‒OAc, as catalyst. Structures of thiosemicarbazones were confirmed by spectroscopic (IR, NMR) methods. The ¹H and ¹³C NMR spectra of substituted acetophenone peracetylated b-lactosyl thiosemicarbazones have been recorded and discussed. The magnetic resonance signals in their NMR spectra show the relationships between the structure and positions of the substituted groups by Hammett’s regression. The b anomeric configuration of these thiosemicarbazones was confirmed on the basis of the coupling constant J = 9.5–8.5 Hz between proton NH-4 of thiosemicarbazone bond and proton H-1’ in lactosyl component.