The thermal behaviour of hydrochlorides of esters (mostly methyl esters) of several naturally occurring 2-amino acids was examined by thermoanalytical methods (DTA, TG, DTG). Heating of the compounds at a constant rate up to 750 K leads to their total or partial volatilization and formation, in the latter case, of a non-volatile residue comprising a mixture of carbonization products. The thermodynamics of the thermal decomposition of the compounds studied was analysed by considering several possible pathways for primary processes. The thermochemical characteristics necessary for these considerations, such as the enthalpies of formation of gaseous 2-amino acid esters and of their crystalline hydrochlorides, were estimated on the basis of the Benson group additivity method and available literature information. Using characteristics thus derived and other data from the literature, the enthalpies of primary processes were evaluated, as well as volatilization temperatures of some of the reaction products. The MINDO/3, MNDO and AMI quantum chemistry methods were applied to evaluate several physicochemical characteristics, in the gaseous phase, for glycine and L-alanine methyl esters and glycine ethyl ester, and also for their protonated forms and decomposition fragments. The thermodynamics of the thermal decomposition of the three above mentioned compounds was then examined using the thermochemical characteristics for gaseous reactants derived by MINDO/3, MNDO and AMI. The AMI method was also applied to analyse structure and energetics of the transition state (saddle point structure) for the decarboxylation of glycine methyl ester. Further, the electrostatic energy of the hydrochloride of L-proline phenylmethyl ester was derived on the basis of the Ewald method and the known crystal structure of the compound. This quantity has been compared with values of crystal lattice energy of hydrochlorides of several other amino acid esters estimated on the basis of the thermochemical cycle using available literature information and the heats of formation of gaseous amino acid esters and their monocations evaluated by quantum chemistry methods.