The structure of the title compound, [Li(BF(4))(CH(3)CN)](n), consists of a layered arrangement parallel to (100) in which the Li(+) cations are coordinated by three F atoms from three tetra-fluoridoborate (BF(4) (-)) anions and an N atom from an acetonitrile mol-ecule. The BF(4) (-) anion is coordinated to three different Li(+) cations though three F atoms. The structure can be described as being built from vertex-shared BF(4) and LiF(3)(NCCH(3)) tetra-hedra. These tetra-hedra reside around a crystallographic inversion center and form 8-membered rings.