Kowalski is the brains of the team; their group strategist and inventor. He's loyal, even if he's not always completely honest about his inventions. He's also highly narcissistic - both confident and boastful about his brains and his looks - so much so that Kowalski will regularly try out his completely untested inventions on himself. Sometimes it ends well. And sometimes... it doesn't. He loves to demonstrate his encyclopedic knowledge of anything and everything, and can be such a show-off that Skipper has created the 'Show-Off Jar', which Kowalski must put a quarter into every time he shows off his intellect unnecessarily.

Kowalski's main disadvantage is that sometimes he over-analyzes things, extensive reasoning getting in the way of acting. Also, he can become too fascinated by science; in the episode Jiggles, he completely loses it when the other penguins become concerned over his latest scientific breakthrough/abomination of nature, calling them "science haters". It was only when Jiggles tried to eat him that he snapped out of it.

Kowalski, as a man of science, does not believe in unproven magic or King Julien's so-called sky spirits. However he has witnessed the supernatural and, while he attempts to find a scientific explanation, he doesn't always succeed, such as in Out of the Groove when King Julien had his Groove removed.

Kowalski is clearly a nerd, and uses many memes popularized by the internet such as "Wehehehel, fail-ail!" (Night and Dazed), "For the win!" (Invention Intervention), and "Holla!" (Friend-in-a-Box). However, due to his nerdiness, all his attempts to be cool sound rather forced. He also tends to use long words. The others are not always able to understand what he is saying, and sometimes ask him to repeat what he's saying in more simple terms.

Though Kowalski is the smartest of the penguins, he lacks the physical endurance of the other penguins, tiring more easily as seen in A Kipper for Skipper. He's convinced that intellect trumps brute force, which brings him into disagreements with Rico.

Despite Kowalski admitting he has trouble expressing his emotions, he still demonstrates strong feelings for others, such as in All Choked Up when he fears that Rico is going to blow up, and by writing bad poetry about a dolphin named Doris - whom he also has a tattoo of. He has been seen kissing with Eva. It is also strongly implied that he once had feelings for a van and gushed "She's beautiful!".[2] On the other hand, in The Otter Woman his main interest in 'Arlene' is scientific as he prepares to study her - while taking her for a nice walk in the park, of course.

Kowalski has the worst luck of the four, but it's mostly brought on by his own arrogance - his inventions frequently blowing up in his face does nothing to keep him from experimenting on himself, such as in Brain Drain. Even so, he can be expected to take hits in other circumstances as well,.

Despite his intellect being the highest of all the penguins, Kowalski can no more read than any of them, although for some reason this doesn't keep him from creating complicated equations, which means he is fluent in mathematics and algebra. The writers seem to have realized how this makes no sense at all, and Kowalski seems to have gained a rudimentary handle on literacy as in later episodes he can interpret road signs and use the Speak and Spell.