Abstract: A one pot process for the preparation of sterically hindered triaryl phosphite is provided. It is suitable for large scale commercial production with an advantage of having carried out the reaction at 0-5° C. in a shortest time of 1 hr using pyridine as Lewis base to remove HCl formed in the reaction; thus avoiding the usage of scrubber. The triaryl phosphite is of the formula P(OR)3 and is produced by reacting a di alkyl—substituted phenol of formula ROH with phosphorus trihalide in a presence of a Lewis base, wherein R represents an aryl compound of a formula C6H3RaRb, wherein Ra is tertiary alkyl, Rb is lower alkyl or tertiary alkyl. The process preferably comprises of mixing a stoichiometric amount of 2,4-dialkyl phenol with phosphorous trihalide in methylene chloride with different stoichiometric amounts of pyridine such as the molar equivalent, 10 mol %, 20 mol % and 50 mol % more than the amount of 2,4 dialkyl phenol. The reaction is preferably carried out at 0-5° C.