The hydrogen bond donating ability of 1,8-naphthalenediol was investigated via a series of H-1, C-13, and P-31 NMR experiments. Complexation studies using triphenylphosphine oxide and cyclohexanone as hydrogen bond acceptors revealed that 1,8-naphthalenediol is a more effective hydrogen bond donor compared to 1-naphthol and 8-methoxy-1-naphthol. Afterwards, its effectiveness as a hydrogen bonding catalyst was demonstrated in the Friedel-Crafts-type addition reaction of indole to trans-beta-nitrostyrene.