Professor Hull in his textbook [Hull, J. C. Options, Futures, & Other Derivatives, Edition 7, Pearson, 2009] illustrates the determination of the credit default swap (CDS) spread by a numerical example. This paper follows the assumptions used by Professor Hull and provides a reduced form formula for the CDS spread. The CDS spread can be simplified by the Taylor series into a function of two variables, the default probability and the recovery rate. Rearranging this simplified formula, the default probability, expressed as the ratio of the CDS spread and the loss given default, is equivalent to the average default intensity, or, the hazard rate defined in Hull [2009, p.500].