We have recorded the third OH-stretching overtone region of vapor phase methallyl- and allyl-carbinol with intracavity laser photoacoustic spectroscopy to investigate the effect of the methyl group in methallyl carbinol on the weak intramolecular OH center dot center dot center dot pi hydrogen bond. We have used atoms in molecules theory, non-covalent interactions calculations and natural bond orbital analysis to describe the intramolecular OH center dot center dot center dot pi hydrogen bond. An increased intramolecular interaction was predicted and confirmed experimentally by an observed larger redshift of the OH-stretching overtone transition of the most abundant conformer of methallyl carbinol relative to that of the corresponding conformer of allyl carbinol. (C) 2013 Elsevier B.V. All rights reserved.