Three papers published in 2015 and 2016 reported the detection of methyl isocyanate (CH₃NCO) in a comet and in different interstellar sources. First, Goesmann et al. reported the detection of methyl isocyanate and fifteen other organic molecules on the surface of comet 67P/Churyumov-Gerasimenko using the mass spectrometer on Rosetta's Philae lander shortly after it reached the surface. (Unfortuantely, a subsequent higher resolution study of comet 67P by Altwegg et al. found no evidence for methyl isocyanate.) Later in 2015, Halfen, Ilyushin, and Ziurys identified the molecule toward Sgr B2(N) (the north complex) via five sequential rotational transtions in each of its rotational conformers. Finally, Cernicharo et al. reported matches to nearly 400 lines of methyl isocyanate toward the Kleinmann-Low region of the great nebula in Orion. The interstellar detections were based on observations made with the ARO 12m telescope, the IRAM 30m telescope, and ALMA. The large number of lines matched by Cernicharo et al. was made possible by a new spectroscopic study of methyl isocyanate. Kolesniková et al. reported a comprehensive study of the rotational spectrum of methyl isocyanide and two of its isotopomers. Methyl cyanide was also detected toward the sun-like protostar IRAS 16293-2422 by Martín-Doménech et al. and Ligterink et al.

Methyl isocyanate and isocyanic acid (HNCO) are related compounds both observed in interstellar sources. While cyanic acid (HOCN) has been observed, a search for methyl cyanate (CH₃OCN) was unsuccessful.

While methyl isocyanate is a stable compound, it is very toxic. The worst industrial accident in history occurred in 1984 when half a million people in Bhopal were exposed to methyl isocyanate released from a Union Carbide India Limited plant.