Castor oil was converted via triglyceride ester-bond cleavage using (i) conventional alkali caustic fusion (NaOH, KOH, CaO) and (ii) a two-step acid–base sequence consisting of sulfuric acid pretreatment followed by alkaline neutralization under harmonized water-equivalent conditions. In both routes, the extent of ester cleavage and the resulting molecular characteristics were systematically evaluated under comparable reaction environments to enable a direct process-level comparison. While caustic fusion induced only moderate changes in apparent molecular-weight indices and led to the formation of THF-insoluble fractions, the sequential acid–base route yielded fully THF-soluble polyols with a significantly lower apparent number-average molecular weight (Mn ≈ 515 g/mol) and a narrow molecular-weight distribution (PDI ≈ 1.09). Molecular-weight distributions and solubility behavior were assessed using THF-based size exclusion chromatography and solvent compatibility tests to elucidate differences in reaction uniformity. This improvement is attributed to effective acid-catalyzed ester cleavage during the initial step, followed by base-mediated stabilization that suppresses re-esterification reactions. As a result, the sequential acid–base process provides a comparative and practical strategy for producing low-molecular-weight, solvent-compatible polyol mixtures from castor oil without the need for multistep purification, highlighting their potential applicability as polyurethane precursors.