Abstract A structural investigation of liquid acetic acid was performed at 298 K using X-ray scattering. To extract the molecular form factor F 1( q), the geometry of the conformer which has been found in the crystal is considered. The pair correlation function clearly shows the signature of hydrogen bonding interactions in liquid acetic acid. The crystal O–H⋯O distance is taken into account and the number of H-bond(s) is assumed to be equal to one and two. The liquid structure can be described by a chain-like trimer similar to the one existing in the crystal; the structure factor S M ( q) extracted from such a cluster where the interactions with neighbouring chains is considered fairly agrees with the experimental one beyond q = 2 Å −1.