Two civilians from Perth have made a spectacular citizens' arrest on an alleged child sex predator at a park.

Police told 9News that the men, aged in their 30s, posed as a 14-year-old boy on dating app Grindr to lure the 61-year-old.

Perth detectives said that they exchanged sexually explicit messages with the 61-year-old and arranged to meet him at Creyk Park in Perth's south-east.

After meeting with the man, the 30-year-olds called Triple Zero and kept him there until police arrived.

Perth Police have since advocated against this behaviour but commended the pair for not hurting the 61-year-old.

After police met the older man, they searched his phone and allegedly located the sexually explicit messages. They then raided his home and seized other electronic devices.

Russ Alan Portelli was refused bail and will front court again next month after being charged with using electronic communication with intent to procure a person under the age of 16 years to engage in sexual activity.