Novel 3-phosphoryloxy-isothiazoles of the formula ##SPC1## Wherein R is selected from the group consisting of alkyl of 1 to 3 carbon atoms, alkoxy of 1 to 3 carbon atoms and ##EQU1## R' and R" being individually SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND ALKYL OF 1 TO 3 CARBON ATOMS, R.sub.1 is alkyl of 1 to 3 carbon atoms, R.sub.2 is selected from the group consisting of hydrogen, alkyl of 1 to 5 carbon atoms, aryl of 6 to 10 carbon atoms, aralkyl of 7 to 12 carbon atoms, cyano, carbalkoxy of 2 to 4 carbon atoms and NHR'", and R'" is selected from the group consisting of hydrogen and aryl of 6 to 10 carbon atoms, R.sub.3 is selected from the group consisting of cyano, alkylthio of 1 to 4 carbon atoms, alkylsulfinyl of 1 to 4 carbon atoms, alkylsulfonyl of 1 to 4 carbon atoms, carbamoyl, carbalkoxy of 2 to 4 carbon atoms and ##EQU2## A and B are individually selected from the group consisting of hydrogen and alkyl of 1 to 3 carbon atoms and X is selected from the group consisting of oxygen and sulfur which have excellent insecticidal properties.