This work investigates the dynamic response of simply supported beam subjected to harmonic excitation by means of rotating unbalance. Passive viscous damper plays crucial role in controlling vibration response of system operating at resonance. Viscous damper containing CuO nanolubricants is used for suppressing the vibrations. Copper oxide (CuO) nanolubricants are prepared by two-stage process, which involves addition of CuO nanoparticles to lubricants and mixing by ultrasonication process for better dispersion stability. Orthogonal array technique is adopted for deciding set of experiments. Experiments are conducted at various speeds and nanoparticle concentrations. RMS acceleration values of the vibrating system are recorded for each experiment. Dynamic performance of the system is compared for various combinations of plain oil, nanolubricants and speed. Results show improved dynamic performance by use of CuO nanolubricants. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.