We describe the advertisement and release calls of Rhinella jimi based on recordings of four individuals from Natal, Rio Grande do Norte State, Brazil. During recordings, we made behavioural observations and used the observed patterns to infer aspects of the mating system of the species. Behavioural patterns suggest that this species is a short, explosive breeder with males actively searching for mates in a scramble competition fashion. Release calls are formed by random combinations of notes that vary in the number of pulses (2–5) and amplitude, but with dominant frequency equal to the advertisement call of the individual. Advertisement calls are formed by trains of repeated pulsed notes with 6.29 ± 2.29 s duration and average dominant frequency of 600.59 ± 51.71 Hz. Calls begin with a rising phase composed of 15.65 ± 7.09 notes during which frequency and amplitude rise to before levelling out along the remaining of the call. The number of pulses per note (2–3) is within the range of several species in the group, but this character likely has a large intrapopulational variation. Rhinella jimi is also similar to R. cerradensis because of its high variation in call duration. However, comparisons are hampered because most call descriptions for members of the R. marina group do not quantify individual or population level variations in call traits. Advertisement calls are fundamental aspects of frogs' natural history, and most likely determinant for the ecology and evolution of the large toads of the R. marina group in South America. Adequate descriptions, quantification of individual and population-level variations, and statistical comparisons are needed before ecological and evolutionary scenarios for these frogs can be proposed and adequately tested.