The nature of the solubilization of β-phenyl-4-mefhoxypropiophenone (1) in the nematic and crystal-B liquid crystalline phases oftrans,trans-4′-butyl-(1, 1′-bicyclohexyl)-4-carbonitrile (CCH-4) has been investigated by deuterium nmr spectroscopy. This has been carried out using deuterium quadrupolar splitting (ΔvQ) andT1measurements on 1–15 mol% solutions of two selectively deuterated derivatives of the ketone in CCH-4 over the 25–110 °C temperature range. The nmr studies have been supplemented with differential scanning calorimetry (DSC) and thermal microscopic investigations of variously proportioned mixtures of the parent ketone with CCH-4, over a similar temperature range. For comparison,2H nmr measurements have also been carried out for solutions of 4-methoxyacetophenone-α,α,α,d3benzene-d6and β-(4-cyclohexylphenyl)-4-methoxypro-piophenone-α,α-d2in the same liquid crystal as a function of temperature. Our results indicate that the limit of solubility of1in the smectic phase of CCH-4 is less than 0.5 mol%. At temperatures above 35 °C, excess ketone is solubilized in a ketone-rich nematic phase that coexists with the bulk smectic phase, and the composition of the ketone-rich phase varies continuously with temperature throughout this range. At around 35 °C, the ketone-rich phase transforms into a metastable, non-birefringent phase which is characterized by isotropic nmr behaviour. Prolonged storage at room temperature causes crystallization of this phase, forming a stable binary mixture of ca. 9:1 CCH-4/1that undergoes a K–Sm transition at 27–28 °C, a Sm–N transition at 43.5–44 °C, and a broad N–Itransition at 58–63 °C. This stable modification can also be prepared by rapid cooling of a 10 mol%1/CCH-4 mixure from the nematic phase. The2H nmr studies of 4-methoxyacetophenone-α,α,α-d3and benzene-d6in CCH-4 indicate that these solutes have somewhat higher solubility in the crystal-B phase of this mesogen. The data necessitate a re-interpretation of our previously reported studies of the excited triplet state behaviour of1in the liquid crystalline phases of this material, and may be broadly applicable to numerous other studies of photochemical reactivity in this mesogen that have been reported.Keywords: liquid crystal, smectic,2H nmr, photochemistry, aromatic ketone, bicyclohexyl-4-carbonitrile,4′-butyl.