Experiments in photocatalysis often involve the use of blacklight UV lamps to simulate the solar UV spectrum under indoor laboratory conditions. solar UV radiometers (such as the Eppley TUVR) which are calibrated for solar UV spectrum require correction when used to measure the energy from a lamp array. This paper describes a transfer calibration procedure that was used to determine instrument response to the blacklight lamp energy spectrum. It also shows theoretically and experimentally that a correction factor of about 1.15 is needed to use a solar UV radiometer for measurements of outputs from the lamps.