Science4You, founded by CEO Miguel Pina Martins in 2008, saw sales of its educational toys jump 52 percent to 21 million euros (18.96 million pounds) last year.

The IPO, offering 44 percent of the company's shares for sale, was launched on Nov. 28 and ends on Friday. Based on an offer price of 2.5 euros per share the company, which is due to be listed on December 21, will be valued at 34 million euros.

"The (IPO) operation is going well," Pina Martins told Reuters. "We know that the markets are unpredictable but we are optimistic, as optimistic as we were at the beginning."

The upbeat comments come just days after fine china maker Vista Alegre withdrew a share offering because of adverse markets. In October, food retailer Sonae cancelled an initial public offering for the same reason.

Pina Martins created Science4You as a part of his university thesis project, raising 55,000 euros in venture capital. Now the company, which mainly sells its products through Amazon, has markets in more than 40 countries and exports account for 70 percent of sales.

Its key markets are in Spain, U.K., Poland and France and its production is mainly in Portugal and Spain.

Pina Martins says he is now eyeing stronger growth in North America.

"We believe our future is in e-commerce with sales through partners like Amazon," he said.

The company makes 500 different toy products, aimed at children from three to 14 years old, including kits such as Soap Factory or Sweet Factory, various build-and-play models from dinosaurs to cars, robots, microscopes and small drones.

Portugal's startup scene is attracting increasing attention as the country pushes to become a technology hub. This year online retailer Farfetch launched an IPO, valuing it at $5.5 billion, and low-code software company OutSystems raised $360 million in funding, valuing it at more than $1 billion.

(Writing by Axel Bugge, editing by Andrei Khalip and Elaine Hardcastle)

By Sergio Goncalves