Aromatic hydrocarbon sensing has been successfully demonstrated using surface plasmon resonance (SPR) with Langmuir-Blodgett (LB) films of a 5,5'-methylenebis (N-hexadecylsaliclidenamine) Schiff base complex. The LB layers were exposed to concentrations of benzene, toluene, ethanol and water vapours. This resulted in a reversible shift in the resonance depth and position of the SPR curves. The co-ordination polymer was found to be most sensitive to benzene and could reliably detect concentrations of this vapour down to 100 vapour parts per million.