Abstract The separation of hydroxybiphenyl isomers was carried out on silica gel. The choice of the separation conditions was difficult owing to the low solubility of the para isomer. Three kinds of the mobile phase were employed, their elution strengths being selected in such a manner that the selectivity factor varied in the range ca. 2.6–7.7. The rate of broadening of a band was investigated as a function of mass overloading and solubility of the sample in the mobile phase for similar k′ values. The optimal column loadability was established for 99.0% purity, taking into account the column throughput and the volume of the fractions. One operation in a 300 × 50 mm I.D. preparative column yielded 1.25 and 0.63 g of pure para and ortho isomers, respectively.