Abstract. A unified integer encoding of ordinal binary trees with integer labels in vertices is given. The encoding is based on the use of linear forms depending on two neighboring members of linear recurrences P_n +2 = α _n +2 P_n +1 + P_n, where P₁=P₂=1; α ₃, α ₄, ... are natural numbers. Encoding and decoding procedures are simple in implementation and use recursive pre-order tree traversal. A brief review of possible applications for subtree processing and cryptographic symmetric encoding is presented .

Keywords: binary trees, encoding trees, linear recurrent sequences, Fibonacci numbers.