In this work, we investigated the influence of positional isomerism on the packing arrangements and the hydrogen bond network in multicomponent crystals of the drug riluzole with hydroxybenzoic acids. A combined theoretical/experimental study, including virtual screening, X-ray diffraction, IR/Raman spectroscopy, thermal analysis and periodic DFT computations, was conducted to isolate and identify the novel crystal forms. By surveying multicomponent crystals of riluzole deposited in the Cambridge Structural Database, we found that salicylic acid derivatives with pKa < 3.8 form salts with riluzole, while benzoic acid derivatives without ortho-hydroxyl groups form cocrystals. New multicomponent crystals of riluzole with salicylic, 4-hydroxybenzoic, 2,3-, 2,4- and 2,6-dihydroxybenzoic acid were obtained and structurally characterized. Varying the experimental conditions allowed us to isolate samples of metastable polymorphs of salts with salicylic, 2,4- and 2,6-dihydroxybenzoic acids. For Form II of the riluzole + 2,6-dihydroxybenzoic acid salt, the crystal structure was determined based on data on powder diffraction of high-energy synchrotron radiation. The hydrogen bond network was found to be identical in riluzole 2,6-dihydroxybenzoate Form I and Form II, and the difference was limited to the mutual orientation of hydrogen-bonded layers, which is a rare example of packing polymorphism. The metastable form was found to undergo an irreversible phase transition at about 120°C, visible as an exothermal event on the thermogram. For riluzole salicylate, two polymorphic modifications were discovered in addition to the already reported form, and the stability relationship between them was studied based on DSC, HSM and dissolution studies. In addition, solvated salt forms were found in the systems with 2,4- and 2,6-dihydroxybenzoic acids during slurry experiments in water, dioxane and DMSO. For the newly obtained phases and pure components, their solubility was determined in aqueous buffer solutions at different pHs and organic solvents, and salt formation thermodynamic functions were obtained from the thermodynamic cycle.