Gum plays a significant role in the feeding ecology of wild callitrichids and thus is also supplemented to several primate species in captivity. However, little is known about the feeding habits of black tufted-ear marmosets (including gummivory), in both wild and captive populations. Therefore, the present study introduced gum to the diet of adult captive black tufted-ear marmosets (Callithrix penicillata), analyzing the influence of gum type (Arabic vs. guar), solution level (50, 25 or 15% m/m gum:water) and time of provision (morning vs. afternoon). Gum intake, latency to first consumption, foraging time/frequency and inter-foraging interval were assessed, as well as changes in body weight. Marmosets were pair-tested in their home-cages and randomly divided into three groups (n = 6): control (water), gum Arabic or gum guar. Water/gum solution was given twice a day (07:30 to 08:30 and 15:00 to 16:00 h), three times a week, during 3 weeks. Each pair was thus submitted to eighteen 30-min trials, with each gum solution being evaluated on three separate occasions during the morning and afternoon periods. Latency to first consumption and foraging were observed only during the first 5-min of each trial. Although water-solubilized gum was promptly consumed, marmosets preferred the Arabic version, with a significantly higher (P < 0.01) and more efficient intake (i.e., greater foraging time/frequency and shorter inter-foraging intervals). Preference was most pronounced for solutions with greater gum content (i.e., 50%). Latency to first consumption (mean ± SEM range: 39 ± 21 to 94 ± 19 s) and body weight (mean ± SEM range: 318 ± 27 to 385 ± 11 g) did not differ within or between groups, and time of provision (morning vs. afternoon) did not influence the results. Intake and foraging were not recorded for the water-treated marmosets. Thus, gum is a viable dietary supplement for captive black tufted-ear marmosets, with attention needed on the type of gum provided, as well as its preparation (solubilization).