The main direction of economic development of our republic is a steep ascent of the national economy on the basis of intensive development of all sectors and accelerating scientific and technological progress, and on this basis, achieving further growth of the welfare of the peoples of Uzbekistan. Cotton production in our country is one of the most important sectors of agriculture. To date, the primary task of technical progress in cotton-growing is mechanized harvesting, in implementation of which an extremely important role is played by pre-harvest chemical defoliation of cotton with the help of chemicals (defoliants). Without this important agrotechnical measure, it is impossible to achieve high productivity of cotton harvesting machines and success in cotton growing at the current stage of cotton cultivation.The purpose of this book is physical and chemical substantiation and development of technology of defoliant production on the basis of 2-chloroethylphosphonic acid, magnesium chlorate, guanidine salt and aminoguanidine.