Detection of the possible melting of gelatin in the temperature range 150Β°-250 Β° is complicated by losses of residual, tightly-bound moisture from specimens and by the occurrence of chemical decomposition. The results of a differential thermal analytical and thermogravimetric analytical investigation of various dehydrated gelatins under an atmosphere of nitrogen have been combined with other auxiliary measurements; these have shown that non-oxidative pyrolysis sets in above 200 Β° when the heating rate is between 1 Β° and 10Β°/min. At 230 Β° 4-_ 3 Β°, gelatin begins to undergo a profound endothermic transformation which reaches its peak at 241 Β° + 4Β°; this transformation, even though resembling melting, is clearly accompanied by irreversible chemical deterioration. Below 200 Β° , this protein can be studied at convenient heating rates without loss of its distinctive chemical nature. The results obtained have been found to be insensitive to the source of gelatin and to several other features of a conventional preparative treatment. It appears, therefore, that the thermal behaviour of gelatin in the range 150Β°-250 Β° is, to a first approximation, characteristic of a unique macromolecular substance in the undiluted (bulk) state.