This paper describes the metrological testing of an electromagnetic velocity transducer, mainly used in forced vibration structural tests performed by LNEC’s Concrete Dams Department. In addition to the brief description of this type of transducer and corresponding mathematical models, the metrological testing results are presented, aiming at the determination of the calibration constant, as well as the evaluation of measurement uncertainty. The obtained results showed a significant reduction of the transducer’s total damping factor, critical damping resistance and sensitivity, which are reflected in the increase of the velocity resolution uncertainty component, being justified by antiquity and frequent use in field dynamic testing. The performed study also allowed the quantification of measurement uncertainties of input, intermediate and output quantities related to this velocity measurement approach. The output signal attenuation was identified as a major uncertainty contribution, therefore showing that particular attention must be given to the electrical calibration of the conditioning unit, also including the regulation of the external resistance.