Upgrade php 5.1 to 5.3 in CentOS

Remove PHP package 

$ sudo yum remove php php-cli php-common php-devel php-gd php-mbstring \
 php-mysql php-mcrypt php-pdo php-pear php-pgsql php-xml php-xmlr

Install PHP 5.3

$ sudo yum install php53 php53-cli php53-common php53-devel php53-gd \
 php53-mbstring php53-mysql php53-pdo php53-pgsql php53-xml php53-xmlrpc 

Restart apache

$ sudo /etc/init.d/httpd restart

Refer:http://chrisjean.com/2011/06/24/upgrade-php-5-1-or-5-2-to-5-3-on-centos/