Apelin, a peptide known for its crucial role in energy balance regulation and contributions to cardiovascular, gastrointestinal, neuroendocrine, and immune functions, has been associated with conflicting outcomes in studies exploring its role in body temperature regulation. Hydrogen sulfide, recognized as a pivotal gasotransmitter, plays a crucial role as a mediator in the regulation of body temperature. In this study, we investigated the impact of systemic intraperitoneal administration of [Pyr¹]apelin-13, the pyroglutamated form of apelin-13, on body temperature in fasted rats. Furthermore, we examined the hypothesis that inhibiting hydrogen sulfide synthesis with the selective cystathionine gamma-lyase inhibitor dl-propargylglycine could modulate the effect of apelin on body temperature. Additionally, we explored the effects of [Pyr¹]apelin-13, both alone and in combination with dl-propargylglycine, on food consumption and body mass gain. Our study demonstrated that the systemic intraperitoneal administration of [Pyr¹]apelin-13 at a dose of 0.5 mg/kg led to a significant increase in body temperature in fasted rats. Importantly, this temperature elevation remained unaffected by the inhibition of cystathionine gamma-lyase with dl-propargylglycine (50 mg/kg, i.p.). Furthermore, the intraperitoneal injection of [Pyr¹]apelin-13 had no discernible impact on food intake but resulted in an increased body mass 24 hours post-injection. Notably, the inhibition of cystathionine gamma-lyase successfully suppressed the apelin-induced rise in body mass in fasted rats. These results provide insight into the intricate regulatory mechanisms involving apelin and hydrogen sulfide, particularly in the context of body temperature and mass modulation during a fasted state.