How long does it take to introduce two cats?

The recommended minimum is two to four weeks, but some pairs take months. Rushing the process is the most common cause of failure. International Cat Care's introduction guide advises progressing only when both cats are relaxed at the current step, however long that takes.

My cats hissed at each other — have I failed?

No. Hissing is normal in the early stages and does not mean the introduction has failed. It is a warning, not an attack. Take a step back in the process and slow down. Fighting — sustained chasing, biting, screaming — is the signal that you have progressed too quickly.

Should I let them "work it out" themselves?

No. Unmanaged introductions frequently result in one cat being injured, developing chronic stress, or hiding permanently. The structured approach in this guide is based on behaviour research and is endorsed by the ASPCA and major veterinary behaviour organisations.

Does gender matter for cat introductions?

Same-sex pairs (especially two males) can be more challenging, but it depends far more on individual personality than sex. Neutered cats of any sex are generally easier to introduce than intact ones. Age gap matters too — a kitten introduced to an older cat is usually easier than adult-to-adult.

How many litter trays do I need for two cats?

The general rule is one tray per cat, plus one extra. For two cats that means three trays, ideally in different locations. Sharing a single tray causes resource guarding and can derail even a successful introduction. See our home setup checklist for full litter guidance.

Introducing a New Cat: A Step-by-Step Guide

Why a slow introduction works

Cats communicate primarily through scent. A new cat arriving in an existing cat's territory is an enormous disruption — the new smell pervades every space and feels like an invasion. The goal of a structured introduction is to let both cats build a scent profile of each other before they ever meet visually, so that the first visual encounter is not also the first scent encounter.

International Cat Care and the ASPCA both recommend this scent-first protocol as the evidence-based standard for cat introductions.

Before the new cat arrives

Set up a dedicated base room with food, water, a litter tray, scratching post, and at least one covered hiding spot
Ensure each cat has its own food bowl, water source, and tray — do not share resources between cats at any stage
Feliway multicat diffuser (synthetic feline facial pheromone) in the main living area may ease tension — see our pheromones glossary entry for how these work

The six-step process

Base room only

Keep the new cat entirely in the base room for at least the first 48 hours. This limits the initial scent invasion and gives the new cat a safe space to decompress from the stress of the journey.

Scent swapping

Rub a clean cloth on each cat (around the cheeks and chin, where scent glands are concentrated) and place it near the other cat's food bowl. Do this daily. Progress to the next step only when both cats eat normally with the cloth present.

Feeding at the door

Move both cats' food bowls to within a metre of each side of the closed base room door. Gradually move them closer until both cats eat at the door without tension. This pairs the other cat's scent with a positive experience.

Space swapping

Confine one cat and allow the other to explore its space. This lets each cat investigate the other's territory, beds, and toys — further mingling scents without direct contact.

Visual contact through a barrier

Use a baby gate, a slightly propped-open door, or a purpose-made mesh barrier. Feed high-value treats (cooked chicken, tuna) during visual sessions. Keep sessions short (2–5 minutes). Stop the moment either cat stiffens, stares, or eats nothing.

Supervised full access

Remove the barrier for short, supervised sessions. Have multiple escape routes — gaps under furniture, high shelves, at least two exits from every room. Never block a cat in or corner it. Stay calm; your body language affects both cats.

Progress marker. Move forward only when both cats are relaxed and eating normally at the current stage. Hissing at the door is normal initially. Only advance when there is none.

What to do if it goes wrong

A chase or a brief swipe is not a crisis. Separate the cats, return to the previous step for a few more days, and try again more slowly. If there are repeated attacks with injury, or if one cat stops eating, consult a veterinary behaviourist. The RCVS specialist finder lists RCVS-accredited feline behaviour specialists in the UK.

Introducing a new cat: a step-by-step guide

Why a slow introduction works

Before the new cat arrives

The six-step process

What to do if it goes wrong

Frequently asked questions