In 2261, Kalomi met Spock, a Vulcan, while on Earth. Kalomi loved Spock, and declared her feelings toward him, but Spock would not allow himself to express any emotion in return. Even after they separated, Kalomi's feelings for Spock would continue.
Kalomi joined Elias Sandoval's Omicron colony in 2263 as the group's botanist. When the colonists made planetfall on Omicron Ceti III in 2264, it was Kalomi who first discovered the Omicron pod plants and the spores they emitted. These spores infected the entire colony, protecting the colonists from the deadly berthold rays bombarding the planet. They also gave every colonist, including Kalomi, a sense of contentment and perfect physical health.
In 2267, when the USS Enterprise arrived at Omicron Ceti III, Kalomi was reunited with Commander Spock, who was serving as the ship's executive and science officer. She used one of the pod plants to infect Spock, breaking down his emotional control, causing him to admit his love for her. The couple spent some blissful time together until Enterprise captain James T. Kirk reversed the spores' hold on Spock by inducing intense anger.
Kalomi attempted to rejoin Spock, but when she found him and realized he was no longer under the influence of the spores, she broke down in tears. The intense sadness she felt caused the spores within her body to be destroyed. Kalomi was later evacuated to Starbase 27 with the rest of the colonists. (TOS: "This Side of Paradise")