Use of atomic force microscopy (AFM) to image surfaces held under electrochemical control in the presence of fluid flow has been demonstrated. The performance of AFM during fluid flow was evaluated on (i) the atomic level (10 to 200 nm) using cleaved mica as the substrate, (ii) on the micron scale (1 to 12 mum) using a gold calibration ruling as the substrate, and (iii) on the micron scale during in situ electrodeposition of Cu onto Pt(100). The Reynolds numbers associated with the fluid flow were evaluated by using the diameter and height of the cell as cross-sectional area, and the hydraulic diameter based on the same area as characteristic length. Maximum Reynolds numbers of 8 for atomic imaging (1 to 25 nm) and 130 for larger scales (1 to 12 mum) may be maintained without loss of imaging quality. The engagement force was the significant parameter which influenced whether images could be obtained during flow. The critical engagement force required for imaging varied linearly with flow rate.