The title compound, [Rh(C8H12)(C18H36P2)]BF4, exhibits a rhodium(I) complex cation with a bidentate bisphosphine ligand and a bidentate eta(2),eta(2)-coordinated cycloocta-1,5-diene ligand. The ligands form a slightly distorted square-planar coordination environment for the Rh(I) atom. An intramolecular P-Rh-P bite angle of 83.91 (2)degrees is observed. The dihedral angle between the P-Rh-P and the X-Rh-X planes (X is the centroid of a double bond) is 14.0 (1)degrees. The BF4 anion is disordered over two positions in a 0.515 (7):0.485 (7) ratio.