Aims Hydrogen sulfide (H 2 S) is a well-known cytotoxic gas. Recently it has been shown to protect neurons against oxidative stress caused by glutamate, hypochlorous acid (HOCl), and beta-amyloid. The aim of the present study is to explore the cytoprotection of H 2 S against 1-methyl-4-phenylpyridinium ion (MPP + )-induced apoptosis and the molecular mechanisms underlying in PC12 cells, a rat cell line derived from pheochromocytoma cells. Main methods Cell viability was determined by the conventional 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay. Apoptosis was assessed by Hoechst 33258 nuclear staining and flow cytometric (FCM) analysis after propidium iodide staining. The mitochondrial membrane potential (MMP) was measured by rhodamine 123 (Rh123) probe and reactive oxygen species (ROS) were measured by dihydrorhodamine probe using FCM analysis. Key findings MPP + reduced the cell viability and induced apoptosis of PC12 cells along with dissipation of MMP as well as overproduction of ROS. Sodium hydrosulfide (NaHS), a H 2 S donor, protected PC12 cells against MPP + -induced cytotoxicity and apoptosis not only by reducing the loss of MMP, but also by attenuating an increase in intracellular ROS. Significance H 2 S significantly protected PC12 cells against cytotoxicity and apoptosis induced by MPP + , which was associated with the inhibition by H 2 S of MPP + -induced dissipation of MMP and overproduction of ROS. These findings can significantly advance therapeutic approaches to the neurodegenerative diseases which are associated with oxidative stress, such as Parkinson's disease.