We investigated the possibility that individual differences in hand preference influence hemispheric emotional valence asymmetries using the Profile of Mood States Short-Form (Shacham, J Pers Assess. 1983;47:305–306) as a measure of emotional valence and tympanic membrane temperature (TMT) as a measure of hemispheric activity. We replicate others' findings of increased negative valence in the non–right-handed. We further demonstrate handedness effects on the absolute difference between left and right TMT, and a positive relationship between this measure and the anger/hostility subscale of the Profile of Mood States Short Form. Findings suggest (i) negative emotional valence is associated with extreme asymmetries of cortical activation and (ii) TMT may be a simple means by which emotional state may be indicated, with increased difference between left and right TMT, suggesting increased anger/hostility. These findings offer the possibility of an exceptionally simple measure that may, in conjunction with more established techniques, offer valuable diagnostic information, particularly for disorders involving anger/hostility.