In order to maintain the high productivity in open offices, which are commonly preferred work environments of modern time, acoustic conditions should be optimized. Especially if work carried out within the premises demands full attention of the employees in open offices, ill-conditioned acoustic conditions can result in loss of concentration and hence degradation in the labour productivity. In this study, one of the open plan offices of Middle East Technical University Registrar's Office was investigated in terms of its acoustic properties, according to the standardisation document TS EN ISO 3382-3 parameters and reverberation time parametre. In order to determine the parameters, office was analysed with real-size measurement on site and the office was simulated with Odeon 10.02 program. Measured results were compared with the simulated results and assessed.