reCaptcha-Controller-2.php

<?php 
   function someAction()
    {
        $this->load->library('form_validation');
        // set validation rule for the recaptcha response
        $this->form_validation->set_rules('recaptcha_response_field', 'reCaptcha', 'required|callback_recaptcha_check');
        if ($this->form_validation->run() === FALSE)
        {
            // store the recaptcha html code for the view
            $data['recaptcha'] = recaptcha_get_html($this->_recaptcha_public_key);
            // pass the data to the view
            $this->load->view('someView', $data);
        }
        else
        {
            // party
        }
    }
?>