WHO's faster than a speeding bullet, more powerful than a locomotive and able to leap tall buildings in a single bound? Krypto the Superdog, of course, star of a new animated series that has its premiere tomorrow at 9 a.m. on Cartoon Network

''I wanted to work with Krypto for a while,'' said Alan Burnett, a writer and a supervising producer on the series, who has also worked on ''The Smurfs,'' ''Static Shock'' and ''Batman: The Animated Series.'' ''We had this image of Superman throwing a stick and having Krypto fetch it from the moon and back.''

Krypto made his debut in a 1955 Adventure Comics story titled ''The Superdog From Krypton,'' and he still occasionally appears by Superman's side. That first comic laid the groundwork for the first episode of the animated series. Krypto is a puppy, bound for space in a rocketship designed by Superman's father, Jor-El. When he awakes from his long journey, he is fully grown, on Earth and gifted with special abilities.

Although Superman will be checking in from time to time, the series is about Krypto's relationship with 9-year-old Kevin Whitney. Krypto and Kevin meet by chance and sense they are both seeking the same thing: companionship. But that's about as far as this show's life lessons go.

''Cartoon Network wanted a comedy-adventure show, heavy emphasis on comedy,'' said Mr. Burnett. ''The lesson part is very tangential. We mostly wanted to give the kids a good time.''

Each episode of the series will be divided into two 11-minute installments. Krypto and Kevin will begin many of their adventures in the Fortress of Doggietude, which is actually Krypto's rocket ship buried in the Whitneys' backyard. But their exploits will take them near and far. In one episode, they must free a teleporter stuck in the diaper of Kevin's baby sister. In another, Krypto must rescue Kevin when aliens adopt him as their pet. Red kryptonite, a radioactive element with unpredictable side effects, will also wreak havoc on their lives, causing, among other things, their minds to switch bodies.

Krypto and Kevin will not be alone in their quest to help keep the human and animal kingdoms safe. ''Krypto has adventures with Bathound, Streaky and the Dog Star Patrol,'' said Mr. Burnett. ''It's a big family of super-animals.''

Streaky, the cat next door that mysteriously gains superpowers, made its debut as Supergirl's pet in February 1960. Ace the Bathound belongs to a certain caped crusader and, like his master, has an arsenal of gadgets at his disposal. The Dog Star Patrol, like Superman's teammates in the Justice League, is a group of super-powered heroes dedicated to fighting the forces of evil. They are based on the Space Canine Patrol Agency from a 1966 ''Superboy'' issue and will appear in several episodes. Their membership includes Brainy Barker, a telepath; Mammoth Mutt, who can grow to gigantic sizes; Tusky Husky, who has a very strong tooth; and Bull Dog, who can sprout horns like a bull.

''Overall, this to me is one of the most successful shows I've ever done,'' Mr. Burnett said. ''I've found a lot of charm in every half-hour, and it was great writing for young kids. If it all goes well, I hope to be doing more.''
George Gene Gustines

Photo: Krypto the Superdog surrounded by friends, including Bathound (far left) and Streaky (front right). (Photo by Cartoon Network and Warner Brothers Animation)