In production of bone implants, there are relatively few of different metal materials being used on account of their proven long-term safety. On the other hand, those materials cover all of the demands put on an implant. The reason for that coverage lies in the fact that the properties of these materials vary considerably depending on the manufacturing processes; shaping, heat treatment and surface engineering. The influence of diverse surface engineering treatments is in the focus of a large number of current studies, with the implant surface being designed specifically to accommodate proper biological response. Basic idea of this dissertation is introductory explained through an overview of the current state in the field of research. Emphasis of this dissertation is set to devising innovative duplex surface engineering treatments as a combination of pack cementation aluminizing and plasma nitriding of Ti6Al4V ELI alloy samples and documenting changes in their potential susceptibility for improvements of osseointegrative behaviour. Changes that have been monitored are surface characteristics that are well known to have an impact on osseointegration of implants: chemical composition, microstructure, roughness, surface free energy and corrosion resistance. The parameters of surface modification treatments are the result of original scientific research, and have yielded success in the implementation of the plasma nitriding and pack cementation aluminizing (both at relatively low temperatures) individually, but also in combining these two methods in novel duplex surface engineering treatments. Changes that have been documented in this research, especially surface morphological changes, changes in surface free energy and roughness in combination with new titanium, aluminum and nitrogen based phases in the outermost layer, are reasonably encouraging for the next stage of in vitro studies with selected cell cultures.