Electronic Journal of Differential Equations, Vol. 2020 (2020), No. 77, pp. 1-34. Title: KdV type asymptotics for solutions to higher-order nonlinear Schrodinger equations Authors: Pavel I. Naumkin (UNAM Campus Morelia, Michoacan, Mexico) Isahi Sanchez-Suarez (Univ. Politecnica de Uruapan, Michoacan, Mexico) Abstract: We consider the Cauchy problem for the higher-order nonlinear Schrodinger equation $$\displaylines{ i\partial_t u-\frac{a}{3}| \partial_x| ^3u-\frac{b}{4}\partial_x^4u =\lambda i\partial_x(| u|^2u),\quad (t,x) \in\mathbb{R}^{+}\times \mathbb{R},\cr u(0,x) =u_0(x),\quad x\in\mathbb{R}, }$$ where $a,b>0$, $| \partial_x| ^{\alpha}=\mathcal{F}^{-1}| \xi| ^{\alpha}\mathcal{F}$ and $\mathcal{F}$ is the Fourier transformation. Our purpose is to study the large time behavior of the solutions under the non-zero mass condition $\int u_0(x)\,dx\neq 0$. Submitted June 2, 2018. Published July 22, 2020. Math Subject Classifications: 35B40, 35Q35. Key Words: Nonlinear Schrodinger equation; large time asymptotic behavior; critical nonlinearity; self-similar solutions.