Here we use near-infrared spectroscopy and chemometric methods of analysis for the measurement of ternary liquid-liquid equilibria. We report data for mixtures of water + sodium hydroxide + an alkanol at 298.15 K and mixtures of water + sodium hydroxide + dimethyl ether at 343.15 K. The alkanols studied were 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, and 2-methyl-1-propanol. The advantage of the method is that all analyses are done in situ, without the need for sampling.