The emergence of the popular culture notion of a sapiosexual, an individual who finds high levels of intelligence (IQ) the most sexually attractive characteristic in a person, suggests that a high IQ may be a genuinely sexually attractive trait, at least for some people. Consequently, mean desirability ratings of IQ on a percentile continuum were estimated, across sexual attraction specifically and long-term partner interest conditions (N = 383). Furthermore, we evaluated the psychometric properties of a newly developed measure, the Sapiosexuality Questionnaire (SapioQ). Finally, we estimated the correlation between objective intelligence and the SapioQ. On average, the 90th percentile of intelligence (IQ ≈ 120) was rated to be the most sexually attractive and the most desirable in a long-term partner. However, 8.1% and 1.3% of the sample scored above 4.0 and 4.5, respectively, on the SapioQ (theoretical range: 1 to 5), which had respectable psychometric properties. The desirability ratings across the IQ percentile continuum interacted with the two conditions (i.e., sexual attraction specifically versus partner interest), such that the rater desirability of IQ increased more substantially for partner interest than sexual attraction specifically across the 25th to 75th IQ percentiles. Finally, objective intelligence correlated negatively with rated sexual attraction specifically and partner interest for a hypothetical person at 25th and 50th percentiles of IQ (r ≈ − 0.25). By contrast, objective intelligence failed to correlate with sapiosexuality (r = − 0.02, p = 0.765; BF01 = 12.84). The results were interpreted to suggest that, for most people, a very high IQ in a partner (IQ 135 +) is not the most attractive level of intelligence, which may be considered supportive of a version of the threshold hypothesis of intelligence. Finally, although sapiosexuality may be a genuine psychological construct, it appears to be influenced by non-intellective factors.