Spectroscopic long-slit observations of the dwarf Irr galaxy IC 10 were conducted at the 6-m Special Astrophysical Observatory telescope with the SCORPIO focal reducer .
The ionized-gas emission spectra in the regions of intense current star formation were obtained for a large number of regions in IC 10 .
The relative abundances of oxygen , N ^ { + } , and S ^ { + } in about twenty HII regions and in the synchrotron superbubble were estimated .
We found that the galaxy-averaged oxygen abundance is 12 + \log ( \textrm { O / H } ) = 8.17 \pm 0.35 and the metallicity is Z = 0.18 \pm 0.14 Z _ { \odot } .
Our abundances estimated from the strong emission lines are found to be more reliable than those obtained by comparing diagnostic diagrams with photoionization models .