This paper focuses on parameter identification of Fluid Viscous Dampers, comparing different existing literature models, with the aim to recognize ability of these models to mach experimental loops under different test specimens. Identification scheme is developed evaluating the experimental and the analytical values of the forces experienced by the device under investigation. The experimental force is recorded during the dynamic test, while the analytical one is obtained by applying a displacement time history to the candidate mechanical law. Identification procedure furnishes device mechanical parameters by minimizing a suitable objective function, which represents a measure of difference between analytical and experimental forces. To solve optimization problem, the Particle Swarm Optimization is adopted, and the results obtained under various test conditions are shown. Some considerations about the agreement of different models with experimental data are furnished, and the sensitivity of identified parameters of analyzed models against frequency excitation is evaluated and discussed.