This invention relates to novel oxyalkylated quaternary ammonium compounds, processes for their production and plant growth regulating compositions containing the same compounds. Each of these oxyalkylated quaternary ammonium compounds consists of an oxyalkylated quaternary ammonium cation and an anion selected from among carboxylic acid residues, aminosulfonic acid residues and phosphoric acid ester residues. These oxyalkylated quaternary ammonium compounds are least phytotoxic, produce marked growth regulating effects on a broad species of plants and are not easily decomposed by microorganisms.