The selectively deuterated, intramolecular coordinated gallane Me2NCH2CD2CH2GaMe2 (1D) was synthesized and characterized by standard methods (H-1 and C-13 NMR, mass spectrometry, CN elemental analysis). The thermolysis of 1D has been investigated with matrix-isolation techniques in the range of ambient temperatures to 950 degreesC. Among the products of the thermolysis the monomeric deuteride DGaMe2 has been identified by IR spectroscopy supported by ab initio calculations. Aside from this deuteride, small amounts of the known hydride HGaMe2 were found. In comparison with known reported data GaMe3, GaMe, H2C=NMe, and H2C=CD(CH2NMe2) have been identified in the matrixes. The characterization of DGaMe2 proves the fragmentation of the starting compound 1D via a beta -hydrogen elimination at high temperatures.