The Python interface to OpenBabel is perhaps the most popular of the several languages that OpenBabel supports.
The rationale and technical details behind Pybel are described in the Pybel paper. To support further development of Pybel, please cite this paper if you use Pybel to obtain results for publication:
N.M. O’Boyle, C. Morley and G.R. Hutchison. Pybel: a Python wrapper for the OpenBabel cheminformatics toolkit Chem. Cent. J. 2008, 2, 5.