This paper presents an experimental investigation of the elastic-plastic out-of-plane buckling response of roller bent circular steel arches subjected to a single force applied to the crown. The experiments are used to validate a finite element model described in a related paper. A series of 15 tests was performed on full-scale and model arches where the developed length of the arches was kept constant. The subtended angle was varied between 90° and 180°. Each full-scale arch configuration was tested at least twice to monitor experimental scatter and assess the repeatability of the tests. Special attention was paid to the boundary conditions: at the crown the load was introduced at the centroid of the arch-rib with the use of hydrostatic bearing to eliminate any torsional restraint. Loading was applied by means of a tension rod affixed to the centre of the baseline, rendering a directed load. The supports were designed such that they acted as hinges in-plane while they were fixed out-of-plane. Geometric imperfections were measured prior to loading. All arches failed by elastic-plastic out-of-plane buckling featuring the presence of plastic zones in the arch-rib and out-of-plane arch deformation.