In spite of being one of the most studied refrigerants, large discrepancies in the experimental determination of the dynamic viscosity of 1, 1, 1,2-tetrafluoroethane (HFC-134a) prevail. Additionally, there is a need for supplementary high-pressure measurements that can help to derive sound general correlations for the viscosity of this compound. Hence, in this work new dynamic viscosity measurements for HFC-134a using a falling-body viscometer in the temperature range of 293.15-373.15 K and pressures up to 140 MPa are presented. This work high-pressure data in combination with already published data provide dynamic viscosity information for the HFC-134a on wide ranges of temperature and pressure. Thus, based on selected HFC-134a viscosity measurements, a representative viscosity model has been correlated using the friction theory (f-theory) in combination with a BWR type of equation of state (EoS). In spite of the discrepancies found in the different data sources, the derived model delivers a reasonably good performance resulting in absolute average deviations around 2%. The derived correlation presented in this work apply to both the liquid and the vapor phases on a temperature range of 200-450 K and for pressures up to 140 MPa. (C) 2003 Elsevier Science B.V. All rights reserved.