Dermacentor reticulatus (Fabr., 1794) (Acari: Ixodidae) is parasite that spreads many diseases which are dangerous to humans and animals. Microelement lithium was found to have promising potential against the detrimental bee pest Varroa destructor. Furthermore, its effectiveness was confirmed against Dermanyssus gallinae, a major parasite of poultry, in vitro. In the present study, we investigated whether the efficacy of lithium chloride extends to other parasitic species, such as D. reticulatus. Our results revealed, for the first time, that the effectiveness of lithium chloride extends to D. reticulatus, confirmed to have 100% mortality at a relatively high minimum concentration of 1.38 M in vitro. The 24 h and 48 h median lethal concentration (LC50) values proved to be 0.654 M and 0.481 M, respectively, for this species. Our pilot study may contribute to a better understanding of the properties of lithium ion. Furthermore, it may elicit further studies aiming to reveal whether the different environmental mineral conditions may influence the D. reticulatus population. Further studies might reveal whether lithium has any possible veterinary relevance.