Abstract: The aim of this work is to find the solvable extensions of the given series of nilpotent Lie algebras of even dimension. The first part focuses on the simplest case, that is six-dimensional one. The second part generalizes the results of the former to arbitrary even dimension of the chosen algebra. One of the aims is the contribution towards the classification of solvable Lie algebras of higher dimensions, the other is to reveal at least a little some properties of solvable Lie algebras in general.