Highly boron-doped diamond films were grown on (100) diamond substrates that were mechanically repolished at an off-axis angle of 4 o with respect to the (100) surface, tilted toward the [110] direction. The surface morphology and crystallinity were examined with atomic force microscopy, and it was found that the deposited surfaces have high crystallinity, with steps running parallel to the [110] direction. The terrace width was ~30nm. Atomic resolution images obtained on these terraces showed a disordered atomic arrangement, with no evidence for the 2x1 or 1x2 reconstruction usually observed for non-doped samples, suggesting that the high level of boron doping affects the surface structure. The electrochemical behavior of the films showed a wide working potential window and low capacitance.