A series of 6-acetyl-2-alkoxy-4H-1,3,2,-benzodioxaphosphorin 2-sulphides (Ila-g) and corresponding 6-bromoacetyl (IIIb-c,g), 6-dibromoacetyl (TVb-c,g) and the reduced 6-acetyl derivatives (Va-c,f) have been prepared from 4-hydroxy-3-(hydroxymethyl)-acetophenone (I). These compounds have been screened for their insecticidal activity.