The new methodology based on Perfumery Ternary Diagram (R) (PTD (R)) used to predict the odor value (OV) of a perfume mixture was updated and validated through experimental measurements of odor threshold values and headspace concentrations, using a perfume test mixture of limonene, geraniol, vanillin, and ethanol. The influence of the odor threshold values on the PTD (R) was considered. The experimental OV values were compared with OV values predicted by PTD (R) model, for the ideal case (considering no molecular interactions) and nonideal case (using UNIFAC model to account for molecular interactions). It was found that PTD (R) results fit reasonably well the experimental data, except for vanillin. Nevertheless, the PTD (R) methodology has proven to be useful in predicting the odor of perfume mixtures and to study the influence of the liquid composition on the headspace compositions, odor values, and its smell. (C) 2007 American Institute of Chemical Engineers.