Self-assembled monolayers (SAMs) consist of densely packed long-chain organic molecules, which are chemisorbed on metal substrates through a sulfur head group. The purpose of this work, is to study the arrangement and structure of SAMs by IR, XPS, NEXAFS, STM, Ellipsometry and contact angle. While the first group of triptycenethiols and the second group of triarylaminethiols show a formation of disordered films on the gold surface, the third group of alkanethioacetates shows the formation of highly ordered monolayers. A further adsorption to upright oriented molecules is hindered due to kinetic effects. In the case of azo-molecules it is shown that the photoisomerization process is not reversible. These molecules are not able to form highly ordered monolayers on the gold surface due to the critical effect of azo-moiety.