This study reports the results of an experimental work carried out with an elastically mounted rigid cylinder exposed to an oscillating flow. To facilitate comparison, the steady current case is included in the test program as well. The oscillatory flow as well as the steady current conditions are created by the so-called carriage technique. The present study covers the Keulegan-Carpenter number range 5 ≤ KC ≤ 100. The range of the reduced velocity is from 0 to approximately 16 in most of the cases. The tests have been conducted for different combinations of spring stiffness and mass of cylinder. The present results shed considerable light into the understanding of the various vibrational response patterns obtained for different ranges of KC number. The response characteristics of the cylinder have been shown to vary extensively, depending on Keulegan-Carpenter number as well as on the reduced velocity.