The wear analyses in microtools remains challenging due to the impossibility of using technical standards applied in macromilling. Moreover, surface finish analysis is crucial when micromachining parts manufactured by additive manufacturing, as this process enhances surface finish and dimensional accuracy. Therefore, this study aimed to analyze the wear and surface roughness in microchannels fabricated through micromilling on AISI H13 tool steel, using a microtool with a diameter of 0.4 mm coated with NaNO3. The tests were performed on CNC milling system with a maximum spindle speed of 60,000 rpm. Minimum Quantity Lubrication (MQL) was employed for cutting fluid application. It uses a cutting speed of 12.6 m/min, feed rate of 5 μm/tooth, radial depth of cut of 400 μm and axial depth of cut of 40 μm. The results showed that the Ra roughness values machining with the NaNO3-coated tool ranged from 0.111 to 0.278 µm. After machining the last channel (130 mm), the wear of the NaNO3-coated tool reached (10.45 ± 2.71) μm. Additionally, no statistical differences were found between the Ra values of the first machined microchannel and the last microchannel. In future work, new experiments with statistical analyses will be conducted to enable complementary analyses.