Gives a report on thermal comfort and IAQ studies of an under-floor air-conditioning (UFAC) system in a hot and humid climate. In order to predict the airflow pattern of the supply air jet and to determine the occurrence of thermal stratification in the office room, thermal comfort parameters were measured at predetermined grid points within an imaginary plane. The authors also used Fanger's thermal comfort index to detect the occupants' thermal sensation, and measurements were made of the concentration levels of dust and carbon dioxide. An attempt was made to derive the relationship between air velocity and the other parameters using statistical methods. States that the results revealed reasonable level of acceptability of indoor air quality associated with the UFAC system. Localised thermal discomfort is likely to be experienced by the occupants, however, near the supply diffusers because of the large temperature gradients. Researchers also discovered a stagnant zone at sedentary level, caused by the parabolic airflow nature of the primary air jet.