You can use tabularx to benefit from all the available hspace. The column with long text can be set X, columns with shorter wrapping text can be set as m{..}, all other columns can be set l. To center any cell use \multicolumn{1}{c|}{..}. Notice the line \renewcommand{\tabularxcolumn}[1]{m{#1}} which redefines X to behave like m. Finally remove \setlength{\tabcolsep}{25pt}, this is responsible for the extra padding to the left and right of cells.
\documentclass[12pt]{article} \usepackage{booktabs,tabularx} \begin{document} \begin{table}[!tbh] \centering \caption{Heuristic techniques}\label{title} %\setlength{\tabcolsep}{25pt} \renewcommand{\tabularxcolumn}[1]{m{#1}} \begin{tabularx}{\textwidth}{|m{1.5cm}|l|X|l|} \hline \textbf{\small Ref. no(s)} & \textbf{\small Objective(s)} & \multicolumn{1}{c|}{\textbf{\small Distinctive attributes}} & \textbf{\small Remarks} \\ \hline Hybrid fdfsadfafdsa \cite{8} & cost & comfortdsaladfjlafjdlkfjldafjdk fjldsajfdlfjdlf & asdf \\\hline hh \cite{9} & Cost & area & enhanced \\ \hline hh \cite{10} & Cost & problems & Practical\\\hline jj \cite{11} & Cost & simplicity & ignored\\\hline jjj\cite{12} & comfort & Cost & S \\\hline kk\cite{13} & Cost & integration & time \\\hline \end{tabularx} \end{table} \end{document} 