The objective of this work is to generate a data base with the spectral classification, UV-to-IR photometry, and Hipparcos astrometry of a large number of Galactic O-type stars. Whenever possible, a single source will be used for each type of data, in order to ensure its uniformity and to allow accurate comparisons. This data base could be used for several purposes, such as the testing of atmospheric models or a study of the extinction law and its spatial variations. We present here the current status of this work as well as our plans for the following months. We plan to upgrade the data base in the future as more O-type stars are classified using the same procedure and more data are obtained from space and ground-based projects. The data base is available at http://www.stsci.edu/~jmaiz.