Abstract This article deals with finding some exact solutions of nonlinear fractional differential equations (NLFDEs) by applying a relatively new method known as G ′ G 2 -expansion method. Solutions of space–time fractional Sharma-Tasso-Olever (STO) equation of fractional order and (3+1)-dimensional KdV-Zakharov Kuznetsov (KdV-ZK) equation of fractional order are reckoned to demonstrate the validity of this method. The fractional derivative version of modified Riemann–Liouville, linked with Fractional complex transform is employed to transform fractional differential equations into the corresponding ordinary differential equations.