Silver is generated in the reactor core during normal operation of very high temperature reactors (VHTRs). It may be transported as aerosols in the reactor circuit and plates out at different points in the reactor including the intermitted heat exchanger. The resuspension of particles in high temperature reactors is closely associated with source term analysis including the environment safety assessment. Adhesion force is important in determining resuspension rate used in resuspension calculations. In this work, the atomic force microscope was used to measure the adhesive force between a spherical silver particle and VHTRs structural materials of Hastelloy X and Inconel 617. These forces were also predicted through the Johnson-Kendall-Roberts (JKR) theoretical model. The theoretically calculated values (when the particle size of 15.1 μm diameter was used) are higher than the measured results by a factor of a 1000. However, when surface roughness was taken into account, an improved comparison between the theoretically predicted values and the measured values was observed. In fact, the comparisons between the theoretically predicted values and the measured results show a deviation that ranges from 0.155 to 0.422 in the case of Hastelloy X and from 0.243 to 0.503 in the case of Inconel 617. The data generated provide insight into the significant influence that surface roughness has on the adhesion force. This adhesion force data may be important in understanding the adhesion of silver particles to Hastelloy X and Inconel 617, and may contribute to particle resuspension calculations.