NOVELTY - Preparation (P1) of a sulfinyl-pyrazole derivative (I) involves oxidizing a substituted amino-4-mercapto-1H-pyrazole compound (II) with an oxidant in the absence of trifluoroperacetic acid.    USE - For preparation of a sulfinyl-pyrazole derivative (claimed) useful for controlling arthropods, plant nematode, helminth or protozoan pests.    ADVANTAGE - The compound (I) exhibits insecticidal properties. The compound (I) can be prepared in high yield by the oxidation of compound (II), but without the need to rely on the use of TFA or its derivatives, as used extensively in the known prior art processes. The oxidant employed in the process avoid the need to use or form trifluoroperacetic acid selected from quinones, such as benzoquinone, peroxides such as hydrogen peroxide, hypohalites such as sodium hypochlorite, or an alkali metal hydroxide such as sodium hydroxide, preferably the oxidant is hydrogen peroxide. The process is friendly and economically viable, convenient, simple and safe method for preparing 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4- trifluoromethyl sulphinyl pyrazole using chemicals which do not corrode the equipment used. Further, the method is carried out at low pressures (such as atmospheric pressure) and temperatures.    DETAILED DESCRIPTION - Preparation (P1) of a sulfinyl-pyrazole derivative of formula (I) involves oxidizing a substituted amino-4-mercapto-1H-pyrazole compound of formula (II) with an oxidant in the absence of trifluoroperacetic acid.    R1=H, cyano, nitro, halo, or acyl;    R2=alkyl, alkenyl, alkynyl, halo substituted alkyl, halo substituted alkenyl, or halo substituted alkynyl;    R3=H or NR6R7;    R4=H, alkyl, aryl, or heteroaryl;    R6 and R7=H, alkyl, alkenylalkyl, alkynylalkyl, formyl, optionally halo substituted alkanoyl, optionally halo substituted alkoxycarbonyl, halo or alkoxymethyleneamin;or    N(R6+R7)=heterocycle.    INDEPENDENT CLAIMS are included for the following:    (1) preparation (P2) of a compound of formula (IV), involving: (A) reacting CF3SCl with a compound of formula (VI) to produce a compound of formula (V); and (B) reacting an oxidant with the compound (V) in a medium comprising trifluoroperacetic acid to produce the compound (IV); and    (2) preparation (P3) of the compound (V), involving: performing step A) of the process (P2).    R9 and R10=halo;    R11=alkyl, alkenyl, alkynyl, halo substituted alkyl, halo substituted alkenyl, or halo substituted alkynyl, preferably 1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 1-6C halo substituted alkyl, 2-6C halo substituted alkenyl, or 2-6C halo substituted alkynyl.