This paper describes tests of thermal comfort and air distribution performance of two relatively new occupant-controlled localized ventilation (also called task ventilation) systems. The first is a raisd-floor distribution system providing air through grilles in the floor panels, and the second is a desk-mounted unit supplying conditioned air at desktop level. The tests were performed in a new controlled environment chamber (CEC) having unique capabilities for detailed studies of space conditioning and thermal comfort in office environments. Measurements were made in a mockup of a typical partitioned open-plan office, and the resulting temperature and air velocity distributions are reported for a variety of system- and locally controlled conditions. Comfort model predictions are presented to describe the degree of environmental control and range of occupant comfort levels produced in the workstations. The results are also compared to those produced by a conventional ceiling supply system. The tests investigated the effects of supply volume, supply location, supply vent orientation, supply/return temperature difference, heat load density, and workstation size and layout. Temperature differences in the range of 1–2.5°C were observed between adjacent workstations, and local air velocities in the vicinity of outlets could exceed 3 m/s. Such wide-ranging values could violate existing comfort standards (ASHRAE, 1981; ISO, 1984), if strictly interpreted. However since these systems put the local thermal conditions within the workstations under the direct control of their occupants, it is recommended that the standards grant exceptions to such systems.