In keeping with the calculations of thermodynamic characteristics of possible transformations of tris(hydroxymethyl)phosphine in the framework of DFT-approach using hybrid exchange-correlation functional B3LYP with the basis 6-311++G** the probability of transformation of tris(hydroxymethyl)phosphine at the temperature below 350 K into methylbis(hydroxymethyl)phosphine oxide is higher than the conversion into methyl(hydroxymethyl)phosphine oxide, and at the temperature over 350 K the trend is opposite. The probability of the formation of a heterocyclic dimer at the temperature over 300 K is somewhat lower and of bis-(hydroxymethyl)phosphine in the temperature range 250-550 K is significantly lower.Tris(hydroxymethyl)phosphine or [bis(hydroxymethyl)phosphanyl]methanol (IUPAC) was prepared for the first time in 1958 by the phosphine reaction with formaldehyde in the presence as catalysts of variable valence metals Pt, Pd, Cd, Ni, Co, Fe or their salts along the Eq. (1) [1].