This paper discusses the design and performance of the time measurement technique and of the synchronization systems of the CMS hadron calorimeter. Timing performance results are presented from the Cosmic Run At Four Tesla and LHC beam runs taken in the Autumn of 2008.
For hadronic showers of energy greater than 100 GeV, the timing resolution is measured to be about 1.2 ns. The inter-channel synchronization is measured to be within 2 ns.