Single-columned Table or Figure after two-columned Text

Use * suffix for the floating element.

 ex:

text text ...................
text text ...................
\begin{table*}[htb]
\caption{}
\begin{tabular}{C{2cm} C{2cm} C{2cm} C{2cm} C{2.1cm} C{2.4cm}}
..........
..........
\end{tabular}
\end{table*}

 Source: http://www.latex-community.org/forum/viewtopic.php?f=35&t=22525