Herbicides have been an integral and important part of agricultural practices. Herbicides are phytotoxic chemicals that are routinely used for unwanted plants and weed control. Herbicides vary in their chemical structure and thus have very distinct difference in toxicity, associated toxicity, mechanism of action, and use. Monuron and diuron belong to phenyl urea class of herbicides these are non-selective systemic herbicides and inhibit photosynthesis. These two herbicides are structurally similar, except number of chlorine(s) in phenyl ring. The presence of an additional chlorine in diuron compared to monuron has prompted for their relative study. This paper involves the relative study of physicochemical properties of monuron and diuron like pKa, microspecies, logP, Hydrophiliclipophilic balance (HLB), pH dependent solubility, lipophilicity, charge range which affect their herbicidal properties. These studies are carried out using Chemaxon-Chemicalize and their persistence using QSAR identifier: VEGAHUB and Toxtree on line web server.