Support for CentOS 6.6 has been introduced for these products:

• ESXi 5.0 Update 3, ESXi 5.1 Update 1, ESXi 5.1 Update 2 , ESXi 5.5, ESXi 5.5 Update 1 and ESXi 5.5 Update 2

For more information about software and hardware support, please check the VMware Compatibility Guide