This study presents a multifractal approach to characterize the structural complexity of 3D surface roughness of electrodeposited Ni-P (10.65 at% P) coatings thermally treated at three temperatures (400°C, 500°C and 600°C), obtained with atomic force microscopy (AFM) analysis. 3D surface roughness was studied in air (ex-situ), on square areas of 2.5 μm x 2.5 μm. The singularity spectrum f(α) provided quantitative values data to characterize the local scale properties of Ni-P coatings surface geometry at nanometer scale. The results showed that the Ni-P coatings (10.6 at% P) that were thermally treated at 500°C possessed the best surface finish. Multifractal analysis provides different yet complementary information to that offered by traditional surface statistical parameters.