In our previous work we investigated the influence of alkaline and 3d transitional metals on the structure and thermal properties of pyridine and pyrazine derivatives [1-3]. Complexes and salts of pyridinecarboxylic, pyrazinecarboxylic and pyridinedicarboxylic acids were investigated [4-5]. The complexations of aromatic carboxylic acids by metal cations changes the electronic charge distribution within the aromatic ring and the carboxylate anion. So far, our studies showed that the effect of metal cation on the electronic structure of pyridine ring of pyridinecarboxylic acids depends on the position of nitrogen atom within the carboxylic acid structure. In the presented work the structure (x-ray), spectroscopic (IRKBr, IRATR) and thermal properties of 2-pyrazinecarboxylic acid and 3-d metal 2-pyrazinecarboxylates were studied. X-Ray diffraction data were collected at 100K and crystal structure was solved and refined. The FT-IR spectra were recorded with an Alfa (Bruker) spectrometer within the range of 400–4000 cm-1. Samples in the solid state were measured in KBr matrix pellets and ATR technique. The products of dehydration and decomposition processes were determined from the TG and DSC curves. Based on bond lengths in an aromatic ring have been calculated aromaticity indices for 3-d metal 2-pirazinecarboxylates. It was compared to the influence of manganese, nickel, cobalt, copper and zinc on an aromatic system of 2-pyrazine carboxylic acid.