You may receive a message prompting you to allow Skype to access information stored in your keychain. Simply click Always Allow and start downloading Skype for Mac OS X.

Your security settings may prevent you from downloading Skype directly from skype.com. In Mac OS X Mountain Lion, these may be set so that they only allow downloads from the Mac App Store:

To change your security settings to allow downloads from places outside of the Mac App Store:

1.    In the menu bar, click the Apple icon and select System Preferences....
2.    In the Personal section, click Security & Privacy.
3.    Select the General tab.
4.    Under Allow applications downloaded from, check Mac App Store and identified developers.

Try using a different browser to download Skype.

Close any applications that use the internet (especially those that might be playing music or video) and cancel any file downloads. If you are using a wireless connection, make sure you have a good signal. Then try again.

Ensure that your browser allows pop-up windows, or add www.skype.com to your pop-up blocker exceptions list.

Temporarily disable any download management software you may be running. You can re-enable this once the download has completed.

Temporarily disable any security software, such as a firewall or antivirus, you may be running. You can re-enable this once the download has completed.

Make sure that you download Skype to a folder on your computer, not to a network drive, which may not be accessible.

Make sure that you have read and write access to the folder you’re downloading to. If you are unsure whether you have read and write access to a location, save the download to the desktop.