Adsorption of calf serum organic matter from a phosphate-buffered solution was studied using the electrochemical quartz crystal microbalance with additional dissipation measurements. Two types of crystal surfaces were used: one rough with micrometer-range surface features and one with roughness in the low nanometer range. The results showed that the adsorption of the organic material was about 1.5 orders of magnitude larger on the rough surface and almost independent of serum concentration in the electrolyte. The adsorption rates were found to increase with increasing serum concentration. For rough crystals, the adsorption kinetics were interpreted with the Johnson-Mehl-Avrami-Kolmogorov model, indicating an initial growth phase according to the t(n)-law, followed by a slower growth as the nucleation sites fill up. This study suggests that specific surface sites are critical to promote adsorption of proteins on a titanium surface. (c) 2021 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).