Pyrazoles are promising model compounds and convenient components for building up supramolecular systems. Due to the presence of an =N–N(H) fragment, pyrazole derivatives possess a unique ability to form various self-associates in the gaseous phase, in crystal, and in solution.1 Studies of such kind have useful applications in pharmacology, typically as non-narcotic analgesics, as well as the field of drug-receptor binding mechanisms in medicinal chemistry.2 Thus, the complexes of pyrazole derivatives with proton donor and acceptors compounds are being studied by many supramolecular chemists. Recently, we obtained an adduct of 3,5-dimethylpyrazole (3,5DMP, an orally active hypoglycemic agent, and effective on carbohydrate and free fatty acid metabolism) with chloranilic acid (CLA, a proton donor). We subsequently investigated the effect of methyl substituents on the packing mode in the adduct, since; either of the methyl groups may have a propensity to be out-of-plane of the pyrazole ring, and thus influence the packing fashion and hydrogen-bond patterns. We also considered how the presence of competitive hydrogen bond donor-acceptor groups can enhance a possible proton transfer process. Thus, in this manuscript the aforementioned aims are discussed. The crystal complex was obtained by dissolving a 1:1 mixture of 3,5DMP (0.20 g, 2 mmol) and CLA (0.42 g, 2 mmol) in 20 ml of methanol and allowed to evaporate slowly at room temperature. Suitable crystals were obtained after eight days, and characterized through X-ray diffraction at 150 K. Crystal data and details of data collection are given in Table 1. The structure solution was carried out with direct methods using the programs SIR 92 or superflip within the CRYSTALS software suite, and refined by full-matrix least-squares methods based on F2. The chemical structure of the adduct is shown in Fig. 1, while the atom numbering follows the scheme indicated in Fig. 2. The bond lengths and angles in CLA are insignificantly different from those in the crystal structure of CLA.3 The geometry of the 3,5DMP ring shows a similar pattern of bond distances and angles as pyrazole,4 and shows an insignificant effect of the hydrogen-bonding interaction on the bonded X-ray Structure Analysis Online