Structural capital is one of the components of intellectual capital. The measurement is essential in order to obtain the real value of intellectual capital and its influence on the profitability of the business. The measurement of structural capital value addition can be done directly or via the mediating effect of another component of intellectual capital, i.e. human capital or relational capital. Human capital has been selected as the mediating component for this study based on findings of previous studies that advocate its importance as a major determinant that enhances structural capital changes. This paper aims at measuring the influence of human capital as a mediating factor on the capacity of structural capital value addition for the period of 2002-2018, for Galicia (Spain) and Portugal.