Physico-chemical and topographical surface quality of commercially pure titanium (c.p. Ti) dental implants is one of the most influencing factors in the improvement of their osseointegration. In this sense, previously, a two-step method (2S) for obtaining bioactive blasted-rough titanium surfaces was developed for improving short-term (due to its bioactivity) and long-term (due to its roughness) osseointegration. This 2S-method consists of: (1) Grit blasting on titanium surface in order to roughen it, and (2) thermo-chemical (TCh) treatment in order to obtain a bioactive surface with bone-bonding ability. The aim of the present work is to evaluate the in vitro human-osteoblast response (proliferation, differentiation - ALP activity- and cell morphology-studied by environmental scanning electron microscopy) of rough c.p. Ti (grit blasted), bioactive c.p. Ti (thermo-chemically treated) and rough-bioactive c.p. Ti (2S-treated). Different grit materials (Al(2)O(3) and SiC) have been used in order to investigate their influence. The results showed that cell adhesion was statistically higher for the rough and bioactive surfaces, whatever the grit used. Cells proliferated very well on all the c.p. Ti surfaces. If comparing groups with and without TCh (all other treatments being equal) the ALP was always higher in the groups with TCh, indicating stimulation of osteoblast differentiation because of TCh, more significantly in the groups that were first blasted. Those ALP results were accompanied by a decrease in the value of proliferation, which shows the good behavior of the cells. This results suggest that a rough and bioactive-titanium surface obtained by 2S-treatment enhances adhesion and differentiation activity of human osteoblasts cells.