Biologically active isoxazoline derivatives were efficiently synthesized in excellent yields and in less reaction time using mild, effective and environmentally friendly butylmethylimidazolium bromide as solvent and catalyst. By use of this catalyst isoxazoline derivatives are produced via cyclization reaction of chalcone and hydroxylamine hydrochloride in ionic liquids media. The separation of the product was facile and the catalyst could be separated and recycled. Our method is very quick, safe and avoids the use of hazardous and expensive reagents and solvents.