In this paper we characterize mixing composition operators acting on the space OM(R)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathscr {O}}_M({\\mathbb {R}})$$\\end{document} of slowly increasing smooth functions. Moreover we relate the mixing property of those operators with the solvability of Abel’s functional equation and we give a sufficient condition for sequential hypercyclicity of composition operators on OM(R)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathscr {O}}_M({\\mathbb {R}})$$\\end{document}. This is used to prove that many mixing composition operators are hypercyclic.