HTBZ-HFU crystallized in the monoclinic P21/n space group, featuring one HTBZ cation and one HFU anion in the asymmetric unit. Figure presents the local environment of the HTBZ cation, showing its hydrogen bonding with two symmetrically equivalent HFU anions. A hydrogen bond is established between HFU and the thiazole N atoms, with an H⋅⋅⋅N bond distance of 1.695(96) Å.