The complex is significant and controlled physicochemical parameters allows the use of nanosizedpowders of metallic iron in different environments. The system "solid - liquid" efficiency of the processdepends on the powder surface wetting. High reactivity, small size and spheroidal particles does not allow to usetraditional methods of determining nanopowders wetting parameters (e.g., contact angle). So urgent is thesearch procedures, which are measured indirectly related to the parameters of the wetting phenomenon.The paper discussed the theoretical background use pH suspension as an analytical signal wetting. The variantsof the pH-metric research. The possibilities of the mathematical treatment of kinetic curves of the pH of theaqueous suspension (pH-unit 150M, the initial acidity of the water is equal to 6.7 ÷ 6.9 units. pH measurementtime is 5 ÷ 10 minutes) for the quality of wetting characteristics (hydrophilicity / hydrophobicity of the surface).It was found that for passivated samples under different conditions, there is a variety of the course of the kineticcurves pH of the slurry and its speed. The differences observed from the first seconds of contact of the powderwith water, which is important for the study of highly reactive nano-sized powders. Different response powderswetting process is explained by the different nature of the acid-base oxide films formed. Proved experimentallythat passivation of metallic iron in an oxidizing atmosphere with different oxygen content forming an oxidecoating of different composition. At low oxygen content formed surface film of magnetite and at high oxygencontent - film of hematite. Various oxides of elements in the ratio Fe:O determines the formation of primary(Lewis) and secondary (Bronsted) acid-base centers surface; different forms hydrate-coated hydroxyl in vivoand affects the forced wetting process (speeds up / slows down).