MICREX DEVELOPMENT CORP.

A mineral exploration and development company operating in Canada and the United States

TSX Venture Exchange symbol "MIX"
SEC 12 g (3) Exemption 82-4281

For immediate release

August 21, 2007

New Mexico Progress Report

Micrex Development Corp. announced today that it has received a preliminary report from exploration work done on 19 claims staked next to its Deadwood/Sunburst Project in New Mexico.

This project is a joint venture between Micrex and Mountain Rio Resources Inc.

The purpose of this exploration program was to map and reconnaissance sample the area to determine if there were areas of exploration interest that could be integrated into the overall Deadwood/Sunburst Project.

The entirety of the recently staked 19 claims was geologically mapped with excellent overall coverage. Detailed notes and GPS waypoints were taken throughout the map area. Outcrops were outlined on 1:2,000 scale map sheets; defined contacts and well constrained inferred contacts were sketched and noted. Old mine workings and smaller scale excavations were mapped and samples taken.

A total of 39 rock samples were taken, representing typical exposures of each mapped rock unit and areas of interest (ie. fracture zones, highly altered intervals, historical excavations and mine workings, vein material, etc.). The rock samples were sent to Acme Analytical Laboratories in Vancouver, BC for analyses (30 elements plus gold and silver geochemical analysis).

It is expected that when drilling starts on the Deadwood/Sunburst Claims the attending Geologist will conduct further work to follow up on this work.

Significant areas of alteration and silicification were noted and more detailed assay results are pending.

Of the assays completed so far one sample has confirmed the strong exploration potential of the newly staked area.

A sample of quartz material taken from a stockpile near an existing historical mine assayed 8.63 grams (0.277 oz.) Gold and 155 grams (4.98 oz.) Silver per metric tonne. It is unknown if the pile was stockpiled ore or tailings from the mine but Micrex has some history on the work there and this result confirms that the early miners had intersected economic ore. Indications are that the mine was not developed to any great extent before World War Two shut down mining in the area as part of the war effort. From the infrastructure remaining it would appear that there has been minimal exploration in and around the existing workings since that time.

Future exploration will evaluate this occurrence and seek others in the area.

The drilling permit is in place for work at the Deadwood/Sunburst Claims and work will begin shortly on access for the drill rig expected to be on site in late August.

Jody Dahrouge of Dahrouge Geological, Edmonton Alberta, has reviewed this press release as the Qualified Person on this Project.

Further information may be obtained from Perry Meszaros or S.E. Marshall at (780) 448-0922
or email at mixinfo-1@mixcorp.com

Web site address: www.mixcorp.com

MICREX DEVELOPMENT CORP.

Peace River Diamond Property • Burmis Magnetite/Titanium Property • St. Charles de Bourget Magnetite/Titanium Property • Fort Steel Placer Property • Bighorn Gold Mine • Banks Gold Mine • Mount Royal Gold Mine • Deadwood Gold Mine • Sunburst Gold Property

THE TSX VENTURE EXCHANGE HAS NOT REVIEWED AND DOES NOT ACCEPT RESPONSIBILITY FOR THE ADEQUACY OR ACCURACY OF THIS RELEASE.

FORWARD LOOKING STATEMENTS

Certain statements in this news release are "forward-looking statements", which reflect management's expectations regarding its property and business operations. All statements other than statements of historical fact contained in this news release are forward-looking statements. Such forward-looking statements involve risks and uncertainties, as they reflect management's current beliefs and are based on information currently available to management. Actual results may differ materially from those anticipated in the statements made. The forward-looking statements are expressly qualified in their entirety by this cautionary statement. The forward-looking statements are made as of the date of this news release and Micrex assumes no obligation to update or revise them to reflect new events or circumstances except as expressly required by applicable securities law. Further information regarding the uncertainties and risks can be found in the disclosure documents filed by Micrex with the securities regulatory authorities, available at www.sedar.com.

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