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Dysregulated appetite is common in autism spectrum disorder (ASD) and it includes excessive interest in tasty foods. Overconsumption of palatable fluids has been found in the valproic acid-induced ASD rat. Though ASD has a strong genetic component, the link between ASD-related genes and appetite for palatable foods remains elusive. We focused on the CNTNAP2gene whose deletion in mice recapitulates human ASD symptoms. We investigated whether Cntnap2−/−male mice consume greater amounts of palatable 10% sucrose, 0.1% saccharin, and 4.1% intralipid solutions offered in episodic meals either in a no-choice paradigm or a two-bottle choice test. We examined how sucrose intake affects c-Fos immunoreactivity in feeding-related brain areas. Finally, we determined doses at which intraperitoneal oxytocin decreases sucrose intake in mutants. In the single-bottle tests, Cntnap2−/−mice drank more sucrose, saccharin, and intralipid compared to WTs. Given a choice between two tastants, Cntnap2−/−mice had a higher preference for sucrose than intralipid. While the standard 1 mg/kg oxytocin dose reduced sucrose intake in WTs, a low oxytocin dose (0.1 mg/kg) decreased sucrose intake in Cntnap2−/−mice. Sucrose intake induced a more robust c-Fos response in wild-type (WT) than Cntnap2−/−mice in the reward and hypothalamic sites and it increased the percentage of Fos-immunoreactivity oxytocin neurons in WTs, but not in mutants. We conclude that Cntnap2−/−mice overconsume palatable solutions, especially sucrose, beyond levels seen in WTs. This excessive consumption is associated with blunted c-Fos immunoreactivity in feeding-related brain sites, and it can be reversed by low-dose oxytocin.