Penicillium simplicissimum (isolate 10, KP713758), a contaminant from indoor wastewater was studied for biosorption and biodegradation activities towards triphenylmethane (TPM) dyes. This newly discovered isolate demonstrated strong decolorization activities towards Methyl Violet (MV, 100mgl-1), Crystal Violet (CV, 100mgl-1) and Cotton Blue (CB, 50mgl-1), with 98 , 95 and 82 removed within 13, 14 and 1 day(s). Malachite Green (MG, 100mgl-1), the most recalcitrant dye, was partially decolorized (54 ) by day 14. The biodegradation potential of P.simplicissimum was detected by the reduction in dye spectra peaks. Induced lignin peroxidase and NADH-DCIP reductase activities further suggested biodegradation potential. Batch studies revealed that decolorization activities of P.simplicissimum were influenced by the biomass used, initial dye concentrations, oxygen availability and cell viability, with optimum decolorization achieved using 2g biomass, 100mgl-1 dye concentration and in the absence of oxygen (except for CB).