New (3+1)-dimensional nonlinear evolution equations with mKdV equation constituting its main part: Multiple soliton solutions

•We develop (3+1)-dimensional equations with mKdV constituting its main part.•We determine multiple soliton solutions.•We examine the constraint conditions for the obtained solutions.

In this work, we present two new (3+1)-dimensional nonlinear evolution equations where the modified KdV equation constituting its main part. We derive the dispersive relation and the phase shift for each model. We determine multiple soliton solutions for each new equation.