COSMOS is an astronomical survey designed to probe the formation and evolution of galaxies as a function of cosmic time (redshift) and large scale structural environment. The survey covers a 2 square degree equatorial field with imaging by most of the major space-based telescopes (Hubble, Spitzer, GALEX, XMM, Chandra) and a number of large ground based telescopes (Subaru, VLA, ESO-VLT, UKIRT, NOAO, CFHT, and others). Over 2 million galaxies are detected, spanning 75% of the age of the universe.This is version 2.1 of the C-COSMOS Bright Source Catalog which consists of 1761 sources detected at uniform confidence in the 0.5 - 7 keV band of the Chandra-COSMOS survey. Details of the survey and initial results are found in the C-COSMOS catalog paper (Elvis et al. 2009, Paper I). The methods used to detect sources and generate the catalog are described in detail in Puccetti et al. 2009 (Paper II). Nearly 100%-complete multiwavelength source identification is discussed in Civano et al. 2009 (Paper III).