Identify the product of Kolbe's reaction from following.

Kolbe's reaction involves the treatment of phenol with sodium hydroxide to form sodium phenoxide.

Sodium phenoxide undergoes electrophilic aromatic substitution with carbon dioxide under pressure and elevated temperature.

Subsequent acidification of the reaction mixture yields salicylic acid (o-hydroxybenzoic acid) as the major product.

Therefore, the product of Kolbe's reaction is salicylic acid.

Answer: Salicylic acid (o-hydroxybenzoic acid)