Multi Wall Carbon Nano Tubes (MWCNTs) have enormous potential in biomedical researches. Structural and size-dependent properties such as length, diameter have notable effects on cytotoxicity which represent major challenge in this field. The aim of this research is evaluation of peroxidase mimic activity of MWCNTs as Nanozyme via Hydroquinone-H2O2 coupled colorimetric system cell viability which was tested on HU02 Human Fibroblast cells using different concentrations of MWCNTs by MTT assay. Results showed MWCNTs had weak catalytic efficiency in aquatic condition and Nanozyme activity of MWCNTs followed Michaelis–Menten curve as peroxidase mimic. Also experimental evidences demonstrated high potency of MWCNTs toxicity so that uptake of MWCNTs concentrations were critical factor in term of dose dependent inhibition of Human Fibroblast cells.