Aim We hypothesized that hydrogen sulphide (H2S), acting specifically in the anteroventral preoptic region (AVPO – an important integrating site of thermal and cardiorespiratory responses to hypoxia in which H2S synthesis has been shown to be increased under hypoxic conditions), modulates the hypoxic ventilatory response. Methods To test this hypothesis, we measured pulmonary ventilation (V˙E) and deep body temperature of rats before and after intracerebroventricular (icv) or intra‐AVPO microinjection of aminooxyacetate (AOA; CBS inhibitor) or Na2S (H2S donor) followed by 60 min of hypoxia exposure (7% O2). Furthermore, we assessed the AVPO levels of H2S of rats exposed to hypoxia. Control rats were kept under normoxia. Results Microinjection of vehicle, AOA or Na2S did not change V˙E under normoxic conditions. Hypoxia caused an increase in ventilation, which was potentiated by microinjection of AOA because of a further augmented tidal volume. Conversely, treatment with Na2S significantly attenuated this response. The in vivo H2S data indicated that during hypoxia the lower the deep body temperature the smaller the degree of hyperventilation. Under hypoxia, H2S production was found to be increased in the AVPO, indicating that its production is responsive to hypoxia. The CBS inhibitor attenuated the hypoxia‐induced increase in the H2S synthesis, suggesting an endogenous synthesis of the gas. Conclusion These data provide solid evidence that AVPO H2S production is stimulated by hypoxia, and this gaseous messenger exerts an inhibitory modulation of the hypoxic ventilatory response. It is probable that the H2S modulation of hypoxia‐induced hyperventilation is at least in part in proportion to metabolism.