The research, conducted by Fay Guarraci, an assistant professor of psychology at Southwestern University, and Staci Benson, a recent graduate there, is the first to examine the interaction between caffeine and sex in females.
The two gave 108 female rats a moderate dose of caffeine, at 15mg/kg, to see what effect this would have on mating.
They found the caffeine shortened the amount of time it took the females to return to the males after receiving an ejaculation, suggesting that the females were more motivated to have sex.
Female rats in a second experiment did not show the same lust for sex when given only 7.5mg/kg of caffeine.
Guarraci said it was tempting to speculate on how caffeine could affect sexual desire in other mammals such as humans, although cautioned that the effects may be less because most humans already consume some caffeine regularly.
"These rats have never had caffeine before. In humans, it might enhance the sexual experience only among people who are not habitual users."
Even so, Guarraci said the study should help scientists to better understand how the brain influences behaviour, and specifically which part influences motivation.
Caffeine has already been widely recognised as a mild stimulant by scientists and the food and drink industry. Almost all energy drinks on the market contain it.
The study may therefore also help food scientists understand more about the way caffeine works on the brain.