To investigate the flexural response of thermally induced (self-excited) bending vibrations of uniformly heated beams in still air, theoretical analyses were carried out considering the nonlinear dependence on the velocity of an unsteady component of the coefficient of heat transfer at the beam surface. Experiments both in air and in vacuum chamber were conducted. The stability boundary derived from the theoretical analysis was determined to be dependent on the phase difference between velocity fluctuations and thermal bending moments, the damping ratio, and a nondimensional parameter related to the heating rate. The experimental investigations showed that this type of thermally induced vibration occurs only in air and does not occur in a vacuum. Deflection responses of the beam were measured for various values of system parameters, and experimental stability boundaries were compared with theoretically predicted results. For long and narrow beams only first-mode bending vibration occurred, but under certain circumstances higher mode bending vibrations were also excited simultaneously on a relatively short beam.