Thermodynamic effects of hydrogen bonding are important in determining the phase behavior in polar fluids. While efforts to understand "strong" donor and "strong" acceptor combinations (H-bonds involving a formation energy mol e negative than - 20 kJ/mol such as alkanol-alkanol H-bonding have been substantial, weak H-bonds (involving double bonds or aromatic rings as proton acceptors) have largely been ignored. Using FTIR spectroscopy H-bonding between alcohol donor and aromatic ring-containing acceptor molecules was studied including l-hexanol and cyclohaxanol at low concentrations where self-association is negligible (strong donors). H-bonding "weak" acceptors studied include toluene and m-xylene. Clear spectroscopic evidence existed for rite formation of H-bonds between the alcohol and aromatic molecules, which are much weaker than conventional "strong donor" - "strong acceptor" H-bonds. Using quantitative FTIR measurements, the percentage of H-bonded alcohol molecules over a range of aromatic concentrations was determined. Ab initio calculations also showed that alcolzol-aromatic H-bonds are much weaker than alcohol-alcohol H-bonds. This H-bonding, though weak, will contribute significantly to the chemical potential of the molecules.