The 5.5.5 version of PHP can be downloaded from Softpedia
PHP, an HTML-embedded scripting language with syntax borrowed from C, Java, and Perl, with a couple of unique PHP-specific features thrown in, has been updated to version 5.5.5.PHP 5.x includes a new OOP model based on the Zend Engine 2.0, a new extension for improved MySQL support, built-in native support for SQLite, and much more.
PHP 5.5.4 features a large number of improvements and fixes. For example, the behavior of static variables in closure generators has been fixed, compiling time errors are no longer triggering the auto loading, the defined interpolation method is used with the generic scaling methods, and a few others more.
You can check out the official changelog in the readme file incorporated in the source package for more details about this release or on the official website. Download PHP 5.5.5 right now from Softpedia.