Contamination of water sources by synthetic dyes is a problem of global concern given their potential toxicities and environmental impacts. A significant increase has been noted in the studies related to developing alternative and efficient systems for the treatment of coloured effluents. This study focused on the development of an environmentally friendly process for the treatment of dye contaminated aqueous media. A natural biosorbent prepared from spent biomass of Pisum sativum was characterized and employed for the removal of a reactive dye for the first time in the literature. Experimental design, modelling and optimization techniques were applied to the batch biosorption process. Process variables were screened using response surface methodology coupled with a Box-Behnken design matrix. Solution pH, biosorbent dosage, reaction time and temperature were considered as key factors. The interactive effects of factor variables on the biosorption, characteristics of the biosorbent and possible dye biosorbent interactions were discussed. The maximum decolourization yield of biomaterial was 83.2% at an initial concentration of 100 mg L-1. The best operating conditions were as follows: pH: 2.0, biosorbent amount: 0.6 g (in 25 mL dye solution), reaction time: 56.9 min and temperature 27.3 degrees C. The Langmuir isotherm model satisfactorily described the equilibrium biosorption data. IR spectra of unloaded and dye-loaded biosorbent indicated the functional groups on the biosorbent, such as a carbonyl that interacted with Reactive Violet 1 dye molecules. SEM micrographs indicated that microprecipitation can also play a role in the decolourization process. This study demonstrates that developed waste biosorbent could be successfully employed as an effective and eco-friendly alternative cleaner to remove reactive dyes from wastewaters. (C) 2015 Elsevier Ltd. All rights reserved.