An analysis is presented to study the unsteady, two-dimensional nanofluid flow of heat and mass transfer with vanishing nanoparticles flux at the wall in the presence of heat generation or absorption with viscous dissipation. In this analysis, it is assumed as nanoparticle flux is zero on the boundaries. The highly nonlinear differential equations governing the boundary layer flow, heat and mass transfer are numerically solved by spectral relaxation method and validated with MATLAB solver bvp4c. The results are obtained by some values of the physical parameters, namely, the Brownian motion parameter, the thermophoresis parameter, unsteadiness parameter, Eckert number, heat generation or absorption parameter, Prandtl number and Lewis number. Physical features for all relevant parameters on the dimensionless velocity, temperature, nanoparticles volume fraction and heat and mass transfer rates are analysed and discussed. The thermal boundary layer thickness increases with an increase in the thermophoretic parameter. The nanoparticle volume fraction profile significantly descends from the surface with an increase in Brownian motion parameter. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.