The title imidazolium-based ionic-liquid salt, C(18)H(24)N(4) (2+)·2BF(4) (-), has the cation lying about a center of inversion. The five-membered imidazole ring is approximately perpendicular to the six-membered phenyl-ene ring [dihedral angle = 86.9 (1)°]. The tetra-fluoro-borate anion is disordered over two sites in a 0.722 (3):0.278 (3) ratio.