The effect of a cooling jet from ceiling on thermal comfort, perception and subjective performance in warm office environment (29.5 °C) was studied. Altogether, 29 participants (13 male and 16 female) participated. All participants were tested in both thermal conditions and the order of the thermal conditions was counterbalanced between the participants. During the experiment, participants filled questionnaires and performed computerised tasks. Using the cooling jet significantly improved the whole body and local thermal comfort. It also improved the perception of the whole working environment. The indoor air was perceived fresher when the cooling jet was provided. Fatigue increased in time significantly only when the cooling jet was not provided. Eye symptoms increased in time only with the cooling jet. The cooling jet increased the sensation of draught, but still the warm room air temperature was perceived to impair the performance more than draught. The room air temperature was perceived to be better for working effectively for a long period of time with the cooling jet.