Troinex has an area, as of 2009[update], of 3.42 square kilometers (1.32 sq mi).

Of the rest of the land, 0.9 km2 (0.35 sq mi) or 26.3% is settled (buildings or roads).

[8] Most of the population (as of 2000[update]) speaks French (1,747 or 86.1%), with German being second most common (80 or 3.9%) and English being third (75 or 3.7%).

[9] As of 2008[update], the gender distribution of the population was 49.2% male and 50.8% female.

In the federal election, a total of 719 votes were cast, and the voter turnout was 55.9%.

[13] In the 2009 Grand Conseil election, there were a total of 1,316 registered voters of which 681 (51.7%) voted.

The most popular party in the municipality for this election was the Libéral with 27.2% of the ballots.

In the canton-wide election they received the highest proportion of votes.

[14] For the 2009 Conseil d'État election, there were a total of 1,316 registered voters of which 758 (57.6%) voted.

[8] There were 964 residents of the municipality who were employed in some capacity, of which females made up 42.6% of the workforce.

In 2008[update] the total number of full-time equivalent jobs was 346.

The number of jobs in the secondary sector was 37 of which 25 or (67.6%) were in manufacturing and 12 (32.4%) were in construction.

In the tertiary sector; 30 or 15.2% were in wholesale or retail sales or the repair of motor vehicles, 6 or 3.0% were in the movement and storage of goods, 18 or 9.1% were in a hotel or restaurant, 2 or 1.0% were in the information industry, 1 was the insurance or financial industry, 11 or 5.6% were technical professionals or scientists, 15 or 7.6% were in education and 18 or 9.1% were in health care.

[8] From the 2000 census[update], 820 or 40.4% were Roman Catholic, while 443 or 21.8% belonged to the Swiss Reformed Church.

The education system in the Canton of Geneva allows young children to attend two years of non-obligatory Kindergarten.

The canton's school system provides two years of non-mandatory kindergarten and requires students to attend six years of primary school, with some of the children attending smaller, specialized classes.

There were 90 lower secondary students who attended school in Troinex.