Sadly, only four issues of his series have been released to date (and they are available on Indyplanet individually or collected as volume 1) and I believe the last one was in early 2014, perhaps even late 2013.
It appears as though the character has gone through intensive restructuring during that time, however. His appearance has changed, the art chores are now being handled by one Myk Emmshin and pages of the fifth issue are being posted on a weekly basis on the publisher's website, presumably to also be made available in print at a later date. The publisher's renewed commitment to the character is further underscored by the merchandise they now offer with his image.
Here are the basics, if you're new to the character.
In January. Two Gargoyles introduced a new series and character, using the same page-a-week format. Meet Spectrum:
I'm trying to avoid reading too much of that book, and the fifth issue of Thunder, because I plan on getting the print versions at some point. But I do know that you can follow Spectrum's adventures from the beginning on this page.