Abstract It is essential to account the variability in thermophysical properties such as thermal conductivity to obtain the characteristics of transport properties in industrial thermal systems more accurately. This phenomenon is especially significant in coating protection for rocket chambers, heat exchangers and power generation, wherein cooling techniques are required for sustaining temperature regulation and structural material integrity. At high operating temperatures, the working fluid and hot walls generally emit appreciable radiation. Mathematical models are therefore required which simultaneously analyse all three modes of heat transfer in addition to viscous flow and a variety of other effects including reactions (corrosion, combustion), mass diffusion and rheological behaviour. The modern thrust in nanoscale materials is a major consideration. Motivated by these applications, in this paper, a theoretical examination is implemented to analyse the impact of thermal conductivity variation and thermal radiation on chemically reacting, free convective Powell-Eyring nanofluid flow over a cylinder. The nanoscale effects are accounted by employing the Buongiorno model. The transformed governing equations are numerically solved by using Keller box method under suitable boundary conditions. The comparison results reveal that the obtained results find an excellent match with the results in the literature. The graphs and tables elucidate the impacts of various pertinent parameters on thermo-solutal transport characteristics. It is to be noted that amplifying thermal conductivity variation rises fluid velocity and temperature. Velocity of the fluid decelerates for elevating Darcy number. Magnifying the radiation corresponds to weak radiative flux and stronger thermal conduction which decrease the heat transfer whereas the mass transfer is increased. Furthermore, nanoparticle concentration decreases with greater first-order chemical reaction and Brownian motion parameter values.