Methyl nitrite (CH3ONO) has received significant experimental and theoretical investigation focused on its existence as two stable conformational isomers resulting from rotation about the primary C-O-N-O dihedral angle. In ambient conditions, both CH3ONO cis and trans rotational isomers can be spectroscopically observed and distinguished from one another using a variety of techniques-gas-and liquid-1 H NMR, UV-Vis absorption, as well as rotational and vibrational spectroscopy-making conformer-specific studies possible. The barrier to cis/trans interconversion in the gas phase is relatively high at ~45 kJ/mol due to contribution of resonance structures with planar C-O-N-O atoms. The relative energies of the two stable conformers differ by ~5 kJ/mol, with cis-CH3ONO being the more stable of the two. Other RONO molecules can exhibit steric repulsions that result in larger differences between conformer energies and thus abundances. In the case of CH3ONO, the cis-CH3ONO conformer is stabilized via internal hydrogen bonding, orienting the N=O portion of the C-O-N-O dihedral towards the methyl group, resulting in a smaller van der Waals diameter than trans-CH3ONO. The determination of conformer abundance of CH3ONO becomes increasingly complicated when moving away from the gas-phase into complex environments such as those found in matrix-isolation spectroscopy. In general, matrix-isolation experiments assume that matrix conformer abundances reflect gas-phase abundances. Upon deposition, this retention of the gas-phase abundance results in matrix abundances that are not in thermal equilibrium at the colder matrix temperature. In some cases the ratio of two or more conformers present in the gas phase can change upon isolation in a low-temperature matrix. Typically this is only observed for chemical systems with a small (< 5 kJ/mol) barrier to isomerization; as the molecules isomerize, their relative conformer abundances equilibrate to the abundances expected at the lower temperature of the matrix. This is a phenomenon known as conformational cooling. For molecules with higher interconversion barriers similar to that seen in CH3ONO, there are typically no significant changes in the conformer abundance between the gas and matrix phases. The complex dynamics of the matrix-formation process and subsequent diffusion of molecules on the surface of a growing matrix are rarely discussed as contributing factors in possible differing conformer abundances between the gas and matrix phases. Theoretical and experimental work focusing on the sticking dynamics, energy transfer, and angle dependence of deposition are typically confined to atoms and molecules sticking to a metal surface or molecular ices, not on inert matrices. To the authors' knowledge, the impact of these factors on conformer abundance in inert matrices has not been quantified.