Abstract The thermal stability of the mRNA-aminoacyl-tRNA-ribosome complex and each of its individual components was examined. A temperature-dependent, reversible dissociation of the mRNA-tRNA-ribosome complex has been demonstrated. By analogy with polynucleotide melting curves, the dissociation of the mRNA-tRNA-ribosome complex is considered as a pseudo-phase transition characterized by a melting temperature, T m . The nature of all three components of the complex affects the T m values. The following factors in the mRNA component were demonstrated to influence the T m of the complex: composition of the codon, the non-codon bases, the chain length, and the position of the terminal phosphate group. A comparison of T m values of the complex for tRNA molecules containing only A–U base pairs in their codon-anticodons indicates that regions of the tRNA molecules outside the anticodon may influence the stability of the complex. The source of the ribosomes modifies the T m of the complex, while the method of preparation of the ribosomes appears to have no effect. The mRNA (trinucleotide)-tRNA-ribosome complex is almost 40 °C more stable than the corresponding trinucleotide-polynucleotide complex in the same buffer.