A novel, rapid method for the analysis of organophosphorus compounds (OPs), as represented by dipterex, was researched and developed with the use of the citrate-capped AgNPs as the effec-tive, analytical probes. The method was based on AChE catalysing acetylthiocholine (ATCh) to form thiocholine (TCh), which is an aggregating agent for AgNPs; this aggregation process is accom-panied by color and UV–vis spectral changes. These key properties are affected by the OPs because these substances inhibit the activity of the AChE, e.g. the absorbance ratio A396/A520is linearly related to the concentration of the OPs. The analysis of the important OP,dipterex, in aqueous medium indicated satisfactory results; also,the method is rapid and apart from on-site analysis capability for monitoring OPs in different waters, there is potential to extend the application of this novel method to fruit and vegetables.