The syntheses, structural characterization, and thermal degradation of a series of the new indium and gallium siloxide dimers [{Me2In(OSiEt3)}2] (1), [{Me2Ga(OSiEt3)}2] (2), [{Me2In(OSi(OtBu)3)}2] (3), [{Me2Ga(OSi(OtBu)3)}2] (4), and In[OSi(OtBu)3)] (5) is reported. Compounds 1–4 are readily accessible by facile Brönsted reaction of InMe3 or GaMe3 with the corresponding silanols Et3SiOH and (tBuO)3SiOH, respectively. Compound 5 could be obtained by analogous protolysis of [In{N(SiMe3)2}3] with an excess amount of (tBuO)3SiOH. The suitability of 1–5 to serve as molecular precursors for low‐temperature synthesis of amorphous indium and gallium oxide for electronic applications was probed. Thus their thermal degradation was studied by Thermogravimetric/differential thermogravimetry analysis (TGA/DTG). Compounds 1–4 were decomposed under dry synthetic air (20 % O2, 80 % N2) at low temperature to yield amorphous indium oxide and gallium oxide particles, respectively. In contrast, thermal degradation of 5 affords amorphous indium silicate. All of these products were analyzed by multiple techniques including powder X‐ray diffraction analysis (PXRD), transmission electron microscopy (TEM), and energy dispersive X‐ray spectroscopy (EDX). Thin‐film field‐effect transistors (FETs) could be fabricated through spin‐coating of silicon‐wafers with solutions of 1 in toluene and subsequent calcination under dry synthetic air at 350 °C. These films exhibit very good FET performance with a field‐effect mobility of 3.0×10−1 cm2 V−1 s and an on/off current ratio of 108.