The thermally induced decomposition of ethoxyethynyl(trimethyl)tin (1) was studied by 119Sn NMR which revealed the formation o f bis(trimethylstannyl) ketene (2) as the major product, bis(trimethylstannyl) acetic acid ethyl ester (3) as a minor product, and a small amount o f tetramethyltin (4). Full NMR data sets, including coupling constants and isotope induced chemical shifts 1Δ12/ 13C(119Sn) are provided for 1-3 . The first example o f ultra-high resolution 119Sn NMR is shown