Try using the lscape and pdflscape packages (lscape is required by pdflscape).
I'm not sure if you'll need to switch to single column first, if so, I'd do it before and after the landscape commands. Without a MWE from you I'm assuming you use multicols. Before the code below I'd put \end{multicols} and after the text below I'd restart the multiple columns with \begin{multicols}{2}
I use something like the below to have a figure page rotated sideways in a PDF document. Not only is the figure rotated, but the page is readable in the resulting PDF.
\begin{landscape} % begin the rotated content.
\begin{figure} % begin content to include on rotated page.
\begin{centering} % Centre the content (not required), personal preference
\includegraphics{some.pdf} % The acutal content
\par\end{centering} % end the centring (remove if \begin{centering} not used)
\protect\caption{\label{fig:aFig}Some PDF Fig} %figure caption
\end{figure} % end of content
\end{landscape} % end rotating
two-columnmode. Also, in my case I need to print a table: do you think it is different from afigurecase? – Py-ser Sep 10 '14 at 02:59\begin{sidewaystable*}to be useful. Do you think it can be of general interest? – Py-ser Sep 10 '14 at 03:50