A chemical vapor deposition reactor and method. Reactive gases, such as gases including a Group III metal source and a Group V metal source, are introduced into the chamber (10) of a rotating-disc reactor and directed downwardly onto a wafer carrier (32) and substrates (40) which are maintained at an elevated substrate temperature, typically above about 400° C. and normally about 700-1100° C. to deposit a compound such as a III-V semiconductor. The gases are introduced into the reactor at an inlet temperature desirably above about 75° C. and most preferably about 100°-350° C. The walls of the reactor may be at a temperature close to the inlet temperature. Use of an elevated inlet temperature allows the use of a lower rate of rotation of the wafer carrier, a higher operating pressure, lower flow rate, or some combination of these.