In the present paper we introduce a quantum analogue of the classical folding of a simply-laced Lie algebra g to the non-simply-laced algebra g σ along a Dynkin diagram automorphism σ of g. For each quantum folding we replace g σ by its Langlands dual g σ ∨ and construct a nilpotent Lie algebra n which interpolates between the nilpotnent parts of g and g σ∨ , together with its quantized enveloping algebra U q (n) and a Poisson structure on S(n). Remarkably, for the pair (g, g σ ∨ ) = (so 2n+2 , sp 2n ), the algebra U q (n) admits an action of the Artin braid group Br n and contains a new algebra of quantum n×n matrices with an adjoint action of U q (sl n ), which generalizes the algebras constructed by K. Goodearl and M. Yakimov in [10]. The hardest case of quantum folding is, quite expectably, the pair (so 8 , G 2 ) for which the PBW presentation of U q (n) and the corresponding Poisson bracket on S(n) contain more than 700 terms each.